https://microbeetechnology.com.au/forum/ Tue, 10 Nov 2026 14:01:18 +0000 MyBB https://microbeetechnology.com.au/forum/thread-1125.html Tue, 03 Nov 2026 11:18:46 +1100 Graham72]]> https://microbeetechnology.com.au/forum/thread-1125.html On the Premium Plus (1024K), I'd like to confirm how port 50h selects the 32 lower-memory banks of 32K, with ROMs off (bit 2 = 1).

Bits 0–1 are clearly bank bits 0–1 (with bit 1 inverted when ROMs are off). For the other three bank bits I've found two different readings:

Bank bit

2 port 50h bit 5 port 50h bit 6
3 port 50h bit 6 port 50h bit 7
4 port 50h bit 7 port 50h bit 5

Thanks g]]> On the Premium Plus (1024K), I'd like to confirm how port 50h selects the 32 lower-memory banks of 32K, with ROMs off (bit 2 = 1).

Bits 0–1 are clearly bank bits 0–1 (with bit 1 inverted when ROMs are off). For the other three bank bits I've found two different readings:

Bank bit

2 port 50h bit 5 port 50h bit 6
3 port 50h bit 6 port 50h bit 7
4 port 50h bit 7 port 50h bit 5

Thanks g]]> https://microbeetechnology.com.au/forum/thread-1120.html Tue, 27 Oct 2026 23:30:01 +1100 shane.crozier]]> https://microbeetechnology.com.au/forum/thread-1120.html
If I dropped a 128k coreboard onto a 32k communicator's baseboard would I expect it to still work?    

In the 80's we dropped our bee's off at the store to get upgraded and it all happened behind the scenes - was it just that simple?]]>
If I dropped a 128k coreboard onto a 32k communicator's baseboard would I expect it to still work?    

In the 80's we dropped our bee's off at the store to get upgraded and it all happened behind the scenes - was it just that simple?]]> https://microbeetechnology.com.au/forum/thread-1113.html Thu, 15 Oct 2026 11:41:08 +1100 fathertedcrilly]]> https://microbeetechnology.com.au/forum/thread-1113.html This in turn requires proper interrupt handling in the z80 core instead of stubs

Having a look across posts in various forums and whatever tech manuals are available,  it seems that all static RAM models tie the reset key to the reset pin.
Whereas dynamic RAM models tie the reset key to the NMI pin.

Is this a fair assumption ?

Thanks
Tony]]> This in turn requires proper interrupt handling in the z80 core instead of stubs

Having a look across posts in various forums and whatever tech manuals are available,  it seems that all static RAM models tie the reset key to the reset pin.
Whereas dynamic RAM models tie the reset key to the NMI pin.

Is this a fair assumption ?

Thanks
Tony]]> https://microbeetechnology.com.au/forum/thread-1112.html Thu, 15 Oct 2026 07:42:02 +1100 Graham72]]> https://microbeetechnology.com.au/forum/thread-1112.html
What I've read so far: the Alpha Plus  and 256TC schematics. On both boards PIO B bit 4 is the serial RXD line, not vsync. PB7 goes through a link (RTC IRQ on both; the Alpha Plus also offers the 6545 LPEN net). On the 256TC, VSYNC is ? an off-sheet signal and I couldn't see it reach the PIO.

Right now the emulator drives port 0x0C bit 5 from one signal, a fixed window at the start of each frame (about 15% in the build I checked). That is an approximation. When I tried a true short VSYNC-width pulse instead, the CF shell's wait ended immediately and its screen never painted.

As Someone notes in an earlier thread I have found disk services have lost data if PB7 is wired.

This is all way above my pay grade so looking for answers. Thanks so much, Graham]]>
What I've read so far: the Alpha Plus  and 256TC schematics. On both boards PIO B bit 4 is the serial RXD line, not vsync. PB7 goes through a link (RTC IRQ on both; the Alpha Plus also offers the 6545 LPEN net). On the 256TC, VSYNC is ? an off-sheet signal and I couldn't see it reach the PIO.

Right now the emulator drives port 0x0C bit 5 from one signal, a fixed window at the start of each frame (about 15% in the build I checked). That is an approximation. When I tried a true short VSYNC-width pulse instead, the CF shell's wait ended immediately and its screen never painted.

As Someone notes in an earlier thread I have found disk services have lost data if PB7 is wired.

This is all way above my pay grade so looking for answers. Thanks so much, Graham]]> https://microbeetechnology.com.au/forum/thread-1087.html Wed, 09 Sep 2026 22:55:24 +1000 someone]]> https://microbeetechnology.com.au/forum/thread-1087.html a slight mod of a 128K DRAM Coreboard and Alpha Plus Base board is configured to punch a neat hole in the memory map for easy PCG access.
e.g PCG being accessed at memory location 8000-BFFF or part thereof.
Bank #0 at 8000-87FF
Bank #1 at 8800-8FFF
Bank #2 at 9000-97FF
Bank #3 at 9800-9FFF
Bank #4 at A000-A7FF
Bank #5 at A800-AFFF
Bank #6 at B000-B7FF
Bank #7 at B800-BFFF

Doing this removes the onerous task of tracking & changing PCG banks continually.
A dedicated I/O port is used to augment the existing memory paging scheme to switch in the PCG.
In conjunction with someone's RA3 mod for 8X8 High PCG memory support and enabling Colour RAM, one can perform fast and easy bitmap graphics.

A useful configuration is:
0000-7FFF used for switched DRAM pages
8000-BFFF used for PCG
C000-EFFF used for DRAM (non-switched)
F000-F7FF used for CHAR or ATTR RAM
F800-FFFF used for COLRAM]]> a slight mod of a 128K DRAM Coreboard and Alpha Plus Base board is configured to punch a neat hole in the memory map for easy PCG access.
e.g PCG being accessed at memory location 8000-BFFF or part thereof.
Bank #0 at 8000-87FF
Bank #1 at 8800-8FFF
Bank #2 at 9000-97FF
Bank #3 at 9800-9FFF
Bank #4 at A000-A7FF
Bank #5 at A800-AFFF
Bank #6 at B000-B7FF
Bank #7 at B800-BFFF

Doing this removes the onerous task of tracking & changing PCG banks continually.
A dedicated I/O port is used to augment the existing memory paging scheme to switch in the PCG.
In conjunction with someone's RA3 mod for 8X8 High PCG memory support and enabling Colour RAM, one can perform fast and easy bitmap graphics.

A useful configuration is:
0000-7FFF used for switched DRAM pages
8000-BFFF used for PCG
C000-EFFF used for DRAM (non-switched)
F000-F7FF used for CHAR or ATTR RAM
F800-FFFF used for COLRAM]]> https://microbeetechnology.com.au/forum/thread-1080.html Mon, 31 Aug 2026 10:47:27 +1000 Graham72]]> https://microbeetechnology.com.au/forum/thread-1080.html
Hoping somebidy can explain for a compact flash edition the correct listing of FDC / CF control address lines.

Some references 0x40 , others 0x44.

A full listing would be appreciated. Thanks g]]>
Hoping somebidy can explain for a compact flash edition the correct listing of FDC / CF control address lines.

Some references 0x40 , others 0x44.

A full listing would be appreciated. Thanks g]]> https://microbeetechnology.com.au/forum/thread-1079.html Sun, 30 Aug 2026 23:29:17 +1000 shane.crozier]]> https://microbeetechnology.com.au/forum/thread-1079.html
The Fileserver II board has connectors on it to match the 40 way (128k Bee) and 50 way (56k Bee ) Server machines

If I'm not mistaken the 56k Microbee drew power from the disk enclosure via the 50 way cable?  - But pins 49/50 in the FileServer II board go to ground and D0 on the PIO?  Were the 56k bee's modified differently to use the FileServer II boards and get their power from a different source?]]>
The Fileserver II board has connectors on it to match the 40 way (128k Bee) and 50 way (56k Bee ) Server machines

If I'm not mistaken the 56k Microbee drew power from the disk enclosure via the 50 way cable?  - But pins 49/50 in the FileServer II board go to ground and D0 on the PIO?  Were the 56k bee's modified differently to use the FileServer II boards and get their power from a different source?]]> https://microbeetechnology.com.au/forum/thread-1075.html Sun, 30 Aug 2026 12:43:41 +1000 shane.crozier]]> https://microbeetechnology.com.au/forum/thread-1075.html
Not sure if this is a result of US tariffs or just devaluation of the aussie dollar but if this keeps up, electronics is going to be a luxury hobby before too long]]>
Not sure if this is a result of US tariffs or just devaluation of the aussie dollar but if this keeps up, electronics is going to be a luxury hobby before too long]]> https://microbeetechnology.com.au/forum/thread-1051.html Sat, 18 Jul 2026 16:23:31 +1000 shane.crozier]]> https://microbeetechnology.com.au/forum/thread-1051.html
Can anyone give the history of the 56k Star Network Server hardware?

From recollection it was the generation of hardware before the 128k SBC was released and had a 50 way ribbon cable to two expansion boxes?

I'm interested if the system ever had access to the hard disk controllers like the SBC eventually did or if the 4 diskette system was the standard hardware that shipped with it.

Are there any photos of one?

It seems there's not much information on this series of servers in our schools, although they are out there..]]>
Can anyone give the history of the 56k Star Network Server hardware?

From recollection it was the generation of hardware before the 128k SBC was released and had a 50 way ribbon cable to two expansion boxes?

I'm interested if the system ever had access to the hard disk controllers like the SBC eventually did or if the 4 diskette system was the standard hardware that shipped with it.

Are there any photos of one?

It seems there's not much information on this series of servers in our schools, although they are out there..]]> https://microbeetechnology.com.au/forum/thread-1046.html Wed, 08 Jul 2026 14:57:54 +1000 headwerkn]]> https://microbeetechnology.com.au/forum/thread-1046.html
A couple of year's back I was given a pair of Microbees by a former workmate, who'd used them for his electrical engineering degree back in the late 1980s and early 1990s. "Pair" is being generous - more like 1.75 units, as you'll soon understand why. Anyhoo, they've sat waiting patiently since then as I finished up my own electrical engineering degree (now complete, thankfully) and I now have some spare time to start the restoration process.


  IMG_5087.jpeg (Size: 212 KB / Downloads: 112)

I'm hoping to use this thread to gather information for how to approach a careful and considered restoration, to get at least the better of the two machines up and running reliably and keep it that way, one that won't unduly risk a system which by all accounts is getting harder to find. I'm reasonably confident and capable with basic electronics, soldering and troubleshooting (a child of Dick Smith's Funway Into Electronics) with mostly audio amps and the like (solid state and valve) but haven't had a lot of experience with serious board-level restoration of computer hardware or digital systems, old or new. The lack of SMD in Microbees is reassuring, to say the least. I've spent many hours watching the likes of Colin @ ThisDoesNotCompute and various others go through the process on various systems, so have a rough idea of what I'm in for. 

Along with the "two" systems I've also been given a period-correct (though non-Microbee-branded) Kaga 12" green monochrome monitor, one and a half power supplies (2 harnesses, 1 transformer), a completed EPROM reader/writer kit and a nice bundle of documentation.

At this stage I've resisted any urge to apply power to anything "just to see", lest I make it worse ;-)

Both systems have 'Model II' on the case. The first system appears intact and unmolested, just a bit dirty and yellowed as you'd expect, shows MB1732-33 ©1983 on the core board and from what I can tell has a full complement of ROMs, and no expansion slot soldered in. From what I can gather from the Wiki, this is a standard 32Kb Series 3 based on the case badging?


  IMG_5035.jpeg (Size: 196 KB / Downloads: 155)  
  IMG_5019.jpeg (Size: 196 KB / Downloads: 114)
  IMG_5020.jpeg (Size: 212 KB / Downloads: 113)

The only damage I can see is a broken 9V battery clip lead. The big 4700uF cap is the only electrolytic I'm seeing; no doubt it'll need replacement however it doesn't appear to have caused any corrosion nearby. Looks like the rest of the board is ceramics/tantalums only, bless whomever did the original design and BOM ;-)


  IMG_5022.jpeg (Size: 212 KB / Downloads: 115)
  IMG_5027.jpeg (Size: 180 KB / Downloads: 170)

Keyboard is an unknown quantity at this stage, by the sounds of things replacement is likely, but all the key caps are in place at least and they're not too gungy.


  IMG_5021.jpeg (Size: 212 KB / Downloads: 122)
  IMG_5024.jpeg (Size: 212 KB / Downloads: 110)

The other system is, umm... well, let's say, it's seen some things ;-)

Both Core and Main boards show plenty of modification and damage (bent pins etc). Exactly what's going on here is beyond my current knowledge... doesn't seem like factory modification/upgrades, more the efforts of a well meaning psychopath with a soldering iron. This was evidently the unit that was used with the EPROM reader, whether the modifications were required to support that peripheral, maybe?

Based on the "vented" top case logo it's apparently a PC85, 64K CIAB or SBC. A sticker on the missing keyboard surround might help. Board codes are PN1632 RevD for the Core and PN1248 for the Main which I'm reading the Wiki correctly indicate an earlier standard model though? Suspect this system might have started life as a bit of a bitsa, and was subsequently abused accordingly.


  IMG_5038.jpeg (Size: 196 KB / Downloads: 112)
  IMG_5039.jpeg (Size: 212 KB / Downloads: 113)
  IMG_5041.jpeg (Size: 212 KB / Downloads: 113)
  IMG_5043.jpeg (Size: 212 KB / Downloads: 110)

Suffice to say it's a mess and quite possibly beyond repair - certainly not without a tonne of work. A number of components seem to be damaged and just getting the Core board to mount would require a plenty of time with a pair of pliers to straighten the interface pins. The board appears to have a decent wad of RAM installed but is missing ROMs? Keyboard is down a few keys too. Likely only good for parts, but we'll get the other unit working first then decide if there's anything that can be done for this one.


  IMG_5049.jpeg (Size: 212 KB / Downloads: 110)
  IMG_5050.jpeg (Size: 196 KB / Downloads: 113)
  IMG_5052.jpeg (Size: 212 KB / Downloads: 103)

The monitor is a Kaga KG-12NA-N. I've managed to find some resources online including a good general reconditioning video including recapping and cleaning out the V/H-HOLD pots. Other than being very dusty internally, it seems fine with no visible burn-in, though someone appears to have bypassed the Power On/Off switch for, uh, some reason. I think a careful cleaning and possibly some recapping will have it running without too much drama.


  IMG_5068.jpeg (Size: 260 KB / Downloads: 112)
  IMG_5067.jpeg (Size: 228 KB / Downloads: 108)
  IMG_5079.jpeg (Size: 212 KB / Downloads: 112)
  IMG_5080.jpeg (Size: 212 KB / Downloads: 108)
  IMG_5082.jpeg (Size: 212 KB / Downloads: 107)
  IMG_5084.jpeg (Size: 212 KB / Downloads: 108)
  IMG_5085.jpeg (Size: 212 KB / Downloads: 115)

The power supply transformer and associated cabling do not inspire confidence. When I get a free moment I'll do some quick tests with a multimeter to check output and continuity, but honestly I'm inclined to just give Ewan some money and get a whole new supply and cable kit when they become available.


  IMG_5054.jpeg (Size: 228 KB / Downloads: 110)
  IMG_5055.jpeg (Size: 212 KB / Downloads: 115)
  IMG_5056.jpeg (Size: 212 KB / Downloads: 263)

So with all that, I'm curious as to what's considered the best plan of attack by the community for restoring old Bees? As it stands, my general plan with the 'good' unit is:

1. Take everything apart, at least to a manageable level.
   
2. Give the PC boards a thorough clean with IPA and a soft brush.
   
3. Replace and resolder the broken 9V battery clip.
   
4. Sort out a dependable power supply and cable set (new or clean up existing).
   
5. Give all the plastics etc. a good clean. (Not interested in retrobrighting.)
   
6. Give the monitor internals a thorough clean, attempt power up, recap as necessary.
   
7. Power up and take it from there. Sounds like keyboard issues are a near-given.
   

Any other suggestions?

Also, I'm guessing a Gotek is the preferred/least complicated way to get programs and data in and out of the Microbee in this day and age? I do have a potentially usable cassette unit (great big Sony unit used for controlling slide projectors) but honestly cassette-based data storage is something I genuinely hated in the 1980s and early 1990s and have zero nostalgia for ;-)

Many thanks if you've read this far - looking forward to people's suggestions and wisdom!

Cheers, Ben.

  IMG_5023.jpeg (Size: 212 KB / Downloads: 178)

  IMG_5025.jpeg (Size: 212 KB / Downloads: 110)

  IMG_5026.jpeg (Size: 212 KB / Downloads: 109)

  IMG_5028.jpeg (Size: 212 KB / Downloads: 111)

  IMG_5029.jpeg (Size: 212 KB / Downloads: 110)

  IMG_5031.jpeg (Size: 212 KB / Downloads: 112)

  IMG_5032.jpeg (Size: 196 KB / Downloads: 109)

  IMG_5033.jpeg (Size: 212 KB / Downloads: 113)

  IMG_5034.jpeg (Size: 212 KB / Downloads: 126)

  IMG_5036.jpeg (Size: 212 KB / Downloads: 111)

  IMG_5037.jpeg (Size: 148 KB / Downloads: 108)

  IMG_5044.jpeg (Size: 212 KB / Downloads: 106)

  IMG_5046.jpeg (Size: 212 KB / Downloads: 104)

  IMG_5057.jpeg (Size: 196 KB / Downloads: 107)

  IMG_5058.jpeg (Size: 212 KB / Downloads: 104)

  IMG_5059.jpeg (Size: 212 KB / Downloads: 107)

  IMG_5061.jpeg (Size: 212 KB / Downloads: 109) ]]>
A couple of year's back I was given a pair of Microbees by a former workmate, who'd used them for his electrical engineering degree back in the late 1980s and early 1990s. "Pair" is being generous - more like 1.75 units, as you'll soon understand why. Anyhoo, they've sat waiting patiently since then as I finished up my own electrical engineering degree (now complete, thankfully) and I now have some spare time to start the restoration process.


  IMG_5087.jpeg (Size: 212 KB / Downloads: 112)

I'm hoping to use this thread to gather information for how to approach a careful and considered restoration, to get at least the better of the two machines up and running reliably and keep it that way, one that won't unduly risk a system which by all accounts is getting harder to find. I'm reasonably confident and capable with basic electronics, soldering and troubleshooting (a child of Dick Smith's Funway Into Electronics) with mostly audio amps and the like (solid state and valve) but haven't had a lot of experience with serious board-level restoration of computer hardware or digital systems, old or new. The lack of SMD in Microbees is reassuring, to say the least. I've spent many hours watching the likes of Colin @ ThisDoesNotCompute and various others go through the process on various systems, so have a rough idea of what I'm in for. 

Along with the "two" systems I've also been given a period-correct (though non-Microbee-branded) Kaga 12" green monochrome monitor, one and a half power supplies (2 harnesses, 1 transformer), a completed EPROM reader/writer kit and a nice bundle of documentation.

At this stage I've resisted any urge to apply power to anything "just to see", lest I make it worse ;-)

Both systems have 'Model II' on the case. The first system appears intact and unmolested, just a bit dirty and yellowed as you'd expect, shows MB1732-33 ©1983 on the core board and from what I can tell has a full complement of ROMs, and no expansion slot soldered in. From what I can gather from the Wiki, this is a standard 32Kb Series 3 based on the case badging?


  IMG_5035.jpeg (Size: 196 KB / Downloads: 155)  
  IMG_5019.jpeg (Size: 196 KB / Downloads: 114)
  IMG_5020.jpeg (Size: 212 KB / Downloads: 113)

The only damage I can see is a broken 9V battery clip lead. The big 4700uF cap is the only electrolytic I'm seeing; no doubt it'll need replacement however it doesn't appear to have caused any corrosion nearby. Looks like the rest of the board is ceramics/tantalums only, bless whomever did the original design and BOM ;-)


  IMG_5022.jpeg (Size: 212 KB / Downloads: 115)
  IMG_5027.jpeg (Size: 180 KB / Downloads: 170)

Keyboard is an unknown quantity at this stage, by the sounds of things replacement is likely, but all the key caps are in place at least and they're not too gungy.


  IMG_5021.jpeg (Size: 212 KB / Downloads: 122)
  IMG_5024.jpeg (Size: 212 KB / Downloads: 110)

The other system is, umm... well, let's say, it's seen some things ;-)

Both Core and Main boards show plenty of modification and damage (bent pins etc). Exactly what's going on here is beyond my current knowledge... doesn't seem like factory modification/upgrades, more the efforts of a well meaning psychopath with a soldering iron. This was evidently the unit that was used with the EPROM reader, whether the modifications were required to support that peripheral, maybe?

Based on the "vented" top case logo it's apparently a PC85, 64K CIAB or SBC. A sticker on the missing keyboard surround might help. Board codes are PN1632 RevD for the Core and PN1248 for the Main which I'm reading the Wiki correctly indicate an earlier standard model though? Suspect this system might have started life as a bit of a bitsa, and was subsequently abused accordingly.


  IMG_5038.jpeg (Size: 196 KB / Downloads: 112)
  IMG_5039.jpeg (Size: 212 KB / Downloads: 113)
  IMG_5041.jpeg (Size: 212 KB / Downloads: 113)
  IMG_5043.jpeg (Size: 212 KB / Downloads: 110)

Suffice to say it's a mess and quite possibly beyond repair - certainly not without a tonne of work. A number of components seem to be damaged and just getting the Core board to mount would require a plenty of time with a pair of pliers to straighten the interface pins. The board appears to have a decent wad of RAM installed but is missing ROMs? Keyboard is down a few keys too. Likely only good for parts, but we'll get the other unit working first then decide if there's anything that can be done for this one.


  IMG_5049.jpeg (Size: 212 KB / Downloads: 110)
  IMG_5050.jpeg (Size: 196 KB / Downloads: 113)
  IMG_5052.jpeg (Size: 212 KB / Downloads: 103)

The monitor is a Kaga KG-12NA-N. I've managed to find some resources online including a good general reconditioning video including recapping and cleaning out the V/H-HOLD pots. Other than being very dusty internally, it seems fine with no visible burn-in, though someone appears to have bypassed the Power On/Off switch for, uh, some reason. I think a careful cleaning and possibly some recapping will have it running without too much drama.


  IMG_5068.jpeg (Size: 260 KB / Downloads: 112)
  IMG_5067.jpeg (Size: 228 KB / Downloads: 108)
  IMG_5079.jpeg (Size: 212 KB / Downloads: 112)
  IMG_5080.jpeg (Size: 212 KB / Downloads: 108)
  IMG_5082.jpeg (Size: 212 KB / Downloads: 107)
  IMG_5084.jpeg (Size: 212 KB / Downloads: 108)
  IMG_5085.jpeg (Size: 212 KB / Downloads: 115)

The power supply transformer and associated cabling do not inspire confidence. When I get a free moment I'll do some quick tests with a multimeter to check output and continuity, but honestly I'm inclined to just give Ewan some money and get a whole new supply and cable kit when they become available.


  IMG_5054.jpeg (Size: 228 KB / Downloads: 110)
  IMG_5055.jpeg (Size: 212 KB / Downloads: 115)
  IMG_5056.jpeg (Size: 212 KB / Downloads: 263)

So with all that, I'm curious as to what's considered the best plan of attack by the community for restoring old Bees? As it stands, my general plan with the 'good' unit is:

1. Take everything apart, at least to a manageable level.
   
2. Give the PC boards a thorough clean with IPA and a soft brush.
   
3. Replace and resolder the broken 9V battery clip.
   
4. Sort out a dependable power supply and cable set (new or clean up existing).
   
5. Give all the plastics etc. a good clean. (Not interested in retrobrighting.)
   
6. Give the monitor internals a thorough clean, attempt power up, recap as necessary.
   
7. Power up and take it from there. Sounds like keyboard issues are a near-given.
   

Any other suggestions?

Also, I'm guessing a Gotek is the preferred/least complicated way to get programs and data in and out of the Microbee in this day and age? I do have a potentially usable cassette unit (great big Sony unit used for controlling slide projectors) but honestly cassette-based data storage is something I genuinely hated in the 1980s and early 1990s and have zero nostalgia for ;-)

Many thanks if you've read this far - looking forward to people's suggestions and wisdom!

Cheers, Ben.

  IMG_5023.jpeg (Size: 212 KB / Downloads: 178)

  IMG_5025.jpeg (Size: 212 KB / Downloads: 110)

  IMG_5026.jpeg (Size: 212 KB / Downloads: 109)

  IMG_5028.jpeg (Size: 212 KB / Downloads: 111)

  IMG_5029.jpeg (Size: 212 KB / Downloads: 110)

  IMG_5031.jpeg (Size: 212 KB / Downloads: 112)

  IMG_5032.jpeg (Size: 196 KB / Downloads: 109)

  IMG_5033.jpeg (Size: 212 KB / Downloads: 113)

  IMG_5034.jpeg (Size: 212 KB / Downloads: 126)

  IMG_5036.jpeg (Size: 212 KB / Downloads: 111)

  IMG_5037.jpeg (Size: 148 KB / Downloads: 108)

  IMG_5044.jpeg (Size: 212 KB / Downloads: 106)

  IMG_5046.jpeg (Size: 212 KB / Downloads: 104)

  IMG_5057.jpeg (Size: 196 KB / Downloads: 107)

  IMG_5058.jpeg (Size: 212 KB / Downloads: 104)

  IMG_5059.jpeg (Size: 212 KB / Downloads: 107)

  IMG_5061.jpeg (Size: 212 KB / Downloads: 109) ]]> https://microbeetechnology.com.au/forum/thread-1042.html Tue, 23 Jun 2026 22:51:29 +1000 shane.crozier]]> https://microbeetechnology.com.au/forum/thread-1042.html
  IMG_1031.png (Size: 158.79 KB / Downloads: 191)

I have been lucky enough to be able to purchase a 'working' 128k Microbee Premium system - however luck comes in different types as it would seem.

I received a new power supply and hooked it up to a Microbee Upscaling video Converter / HDMI to my screen and the only thing displayed is the infamous solid block in the top left of the screen ...


  IMG_1032.png (Size: 121.36 KB / Downloads: 174)

Reset key doesn't seem to do anything, and applying power with the M key depressed seems to have no effect either - all and any suggestions appreciated .]]>
  IMG_1031.png (Size: 158.79 KB / Downloads: 191)

I have been lucky enough to be able to purchase a 'working' 128k Microbee Premium system - however luck comes in different types as it would seem.

I received a new power supply and hooked it up to a Microbee Upscaling video Converter / HDMI to my screen and the only thing displayed is the infamous solid block in the top left of the screen ...


  IMG_1032.png (Size: 121.36 KB / Downloads: 174)

Reset key doesn't seem to do anything, and applying power with the M key depressed seems to have no effect either - all and any suggestions appreciated .]]> https://microbeetechnology.com.au/forum/thread-1040.html Mon, 15 Jun 2026 22:23:23 +1000 aladinsane]]> https://microbeetechnology.com.au/forum/thread-1040.html
New to the forum and new to Microbees - so in general just a newbee (sorry, couldn't resist...)

I recently got hold of two Microbees without any accessories besides a big stack of games. The two machines was in a dirty state and after having found out PSU needs and the wiring of the DIN-connector, they also it turned out quite dead  

The machines are almost identical. Both have a revision H mainboard. One as a 32k core board and the other a 16k core board. An one has a RF-modulator and some alteration to the cassette-circuit.

Luckily the batteries were intact and hadn't leaked any acid. On both machines one of the two LM7805 had caused a short, so I replaced them with a pin compatible 5v-dc-dc module. I gave both machines a good scrub (IPA, vinegar and soap) and after that I have +5v on the 5v-rail, +10.5v om the unregulated 10v-rail and 11.5v on the 12v-rail. 

Z80 cpu is confirmed working (I tested it in a Sinclair ZX81) and I have checked for life on RESET and CLK but IORQ (pin 20) is dead. CRCT (6545) gets 12Mhz clock signal but does not provide and SYNC signals on pin 39 & 40. So there is life, but no screen output

I have also dumped the EPROMS and they seem to be valid. 

Are there any common errors with aging Microbees? Or does anyone have any ideas as to what I should try/look for? I suspect the 6116 RAM chips, but it requires desoldering and I'm a bit afraid of the risk of damaging the board by removing so many 24p chips.


  IMG_5385_32k.jpeg (Size: 405.22 KB / Downloads: 126)


  IMG_5383_16k.jpeg (Size: 374.58 KB / Downloads: 129) ]]>
New to the forum and new to Microbees - so in general just a newbee (sorry, couldn't resist...)

I recently got hold of two Microbees without any accessories besides a big stack of games. The two machines was in a dirty state and after having found out PSU needs and the wiring of the DIN-connector, they also it turned out quite dead  

The machines are almost identical. Both have a revision H mainboard. One as a 32k core board and the other a 16k core board. An one has a RF-modulator and some alteration to the cassette-circuit.

Luckily the batteries were intact and hadn't leaked any acid. On both machines one of the two LM7805 had caused a short, so I replaced them with a pin compatible 5v-dc-dc module. I gave both machines a good scrub (IPA, vinegar and soap) and after that I have +5v on the 5v-rail, +10.5v om the unregulated 10v-rail and 11.5v on the 12v-rail. 

Z80 cpu is confirmed working (I tested it in a Sinclair ZX81) and I have checked for life on RESET and CLK but IORQ (pin 20) is dead. CRCT (6545) gets 12Mhz clock signal but does not provide and SYNC signals on pin 39 & 40. So there is life, but no screen output

I have also dumped the EPROMS and they seem to be valid. 

Are there any common errors with aging Microbees? Or does anyone have any ideas as to what I should try/look for? I suspect the 6116 RAM chips, but it requires desoldering and I'm a bit afraid of the risk of damaging the board by removing so many 24p chips.


  IMG_5385_32k.jpeg (Size: 405.22 KB / Downloads: 126)


  IMG_5383_16k.jpeg (Size: 374.58 KB / Downloads: 129) ]]> https://microbeetechnology.com.au/forum/thread-1033.html Sat, 23 May 2026 16:26:59 +1000 shane.crozier]]> https://microbeetechnology.com.au/forum/thread-1033.html https://microbeetechnology.com.au/forum/thread-1025.html Fri, 15 May 2026 11:52:05 +1000 shane.crozier]]> https://microbeetechnology.com.au/forum/thread-1025.html
  Amber_monitor.jpg (Size: 39.82 KB / Downloads: 149)

I've purchased an Amber Monitor on Ebay with some image sync issues - I'm going to try to repair it (looks like its been exposed to a lot of dirt, so it might just need a good clean and touching up solder joints)

Do we have a schematic / manual for these available ?]]>
  Amber_monitor.jpg (Size: 39.82 KB / Downloads: 149)

I've purchased an Amber Monitor on Ebay with some image sync issues - I'm going to try to repair it (looks like its been exposed to a lot of dirt, so it might just need a good clean and touching up solder joints)

Do we have a schematic / manual for these available ?]]> https://microbeetechnology.com.au/forum/thread-1020.html Mon, 04 May 2026 10:07:55 +1000 shane.crozier]]> https://microbeetechnology.com.au/forum/thread-1020.html
Does anyone have a StarNet Network adapter pcb diagram or a physical adapter?

Hoping to find one of these so I can potentially setup a "Yesteryear's classroom" demonstration.

Cheers]]>
Does anyone have a StarNet Network adapter pcb diagram or a physical adapter?

Hoping to find one of these so I can potentially setup a "Yesteryear's classroom" demonstration.

Cheers]]>