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+--- Thread: Upgrading a Microbee PC85 to a PC85b and adding extra Game ROMs. (/thread-366.html)
RE: Upgrading a Microbee PC85 to a PC85b and adding extra Game ROMs. - ChickenMan - 28-08-2021
Assuming you have a 8328-4 or -6 coreboard, there is nothing to do other than burn out out PC85b Roms E, F, G, H & I with F & G needing 27128 eproms and the others 2764's. Your already installed a heat sink under the regulator, all you need now is some 27128 or 27c128 eproms. We have a few game ROMs (some original and some I have made) in the repository plus others. See the eprom_programmer_and_64k_rom_pak_instruction_manual.pdf for the procedure on how to make your own eproms. I just burnt out the Micro Defender game to a 27128 having to split it into 2 x 8k parts and which I will put in the Rom H (Viatel) socket and add a game in the 2nd 8k part of roms E & I and now looks like
The Engineering Notes I mentioned are in engineering_change_notices_85.zip in the MbeeTech Repository in the \Microbee\Documentation\Manuals\Technical folder. The PDF is Searchable (as are all of our PDF's), so just do a search for PC85 and you will find it all.
RE: Upgrading a Microbee PC85 to a PC85b and adding extra Game ROMs. - CheshireNoir - 26-09-2021
Possibly a silly question: What order do the ROMs go in the sockets?
I'm only getting MW Basic, but that may be because I've been "playing" a bit with the ROM spaces. I just want to eliminate obvious eror.
I have them in the following:
ROM E - IC25
ROM F - IC27
ROM G - IC24
ROM H - IC23
ROM I - IC22
(I piggybacked Kilopede on the back of E, Space Invaders on H and Survivor on I. I figured those were all 8K ROMs so I should be fine. This may not be the case :-D )
Thanks everyone! Adventure!
Chesh
RE: Upgrading a Microbee PC85 to a PC85b and adding extra Game ROMs. - Ernest - 26-09-2021
Hi Chesh,
The second bank (top 64K are as follows)
ROM E - IC25 Lower = Pak1 - Upper = Pak9
ROM F - IC27 Lower = Pak5 - Upper = Pak13
ROM G - IC24 Lower = Pak2 - Upper is reserved for the PC85b MENU
ROM H - IC23 Lower = Pak3 - Upper = Pak11
ROM I - IC22 Lower = Pak4 - Upper = Pak12
The ones above are wrong, below is the correct layout.
The second bank (top 64K are as follows)
ROM E - IC25 Lower = Pak1 - Upper = Pak9
ROM F - IC24 Lower = Pak2 - Upper is reserved for the PC85b MENU
ROM G - IC23 Lower = Pak3 - Upper = Pak11
ROM H - IC22 Lower = Pak4 - Upper = Pak12
ROM I - IC27 Lower = Pak5 - Upper = Pak13
Ernest
RE: Upgrading a Microbee PC85 to a PC85b and adding extra Game ROMs. - CheshireNoir - 26-09-2021
Huh. Wonder why it doesn't work for me? Maybe those double sized ROMs I fitted are interfering with something...
The system is a 8328-4 core so no changes should be needed? I did read the tech note and it suggested I should only need new ROMs (As also suggested by ChickenMan above)
I concatenated the ROMs under DOS with "copy /b file1.bin+file2.bin outfile.bin" and I can run Space Invaders (PAK 11, behind H) and Kilopede (PAK 9, behind E) but Survivor doesn't work (PAK 12, behind I).
No Menu on bootup and I can't seem to "PAK" to the menu either.
I'm a bit stumped...
Chesh
EDIT: I notice PAK4 is not working. Going to reburn "ROM I" as that's also the one not working for Survivor so something "odd" going on there. I've checked the socket for continuity and that seems fine...
EDIT2: I have reburned the ROM I. The original was corrupt. I still don't get the menu but I do get Survivor now. PAK4 doesn't seem to do anything interesting. I'll now pull out ROM G and do another verify on it, just in case.
EDIT3: F and G verify fine.
RE: Upgrading a Microbee PC85 to a PC85b and adding extra Game ROMs. - Ernest - 26-09-2021
Hi Chesh,
Try swapping over the H & G ROMs position is not important for these two they will just show up in different locations on the MENU.
If the problem swaps with the ROM then the problem is with the ROM if the problems stays with the ROM location then you have a decoding issue to that ROM slot.
When you say "No Menu on bootup and I can't seem to "PAK" to the menu either." Is this still the case after fixing the bad ROM I?
If any of the ROM addressing or images are a problem it can prevent the system booting to the SHELL as part of the boot up is to verify all the ROMs that are present
The boot up "MENU" as you call it is called the "Shell" this can be arrived at from BASIC with the PAK5 call. The MENU ROM PAK10 can't be called normally and a PAK10 will give "option not fitted" response.
If a ROM is not showing up in the Shell it may still be available and working but accessible by hitting RETURN at the Shell which will list the directory from here you can navigate to all available programs.
I suggest that you pick a location that is working fine (Like ROM E) and use this location to test any new double bank ROMs you set up.
Additionally you can use a known working double bank ROM in each of the H & G locations. Locations F & I this technique will not work as they have the SHELL & MENU in them.
I really don't know why they didn't put these two as banks in the same ROM.
Ernest
RE: Upgrading a Microbee PC85 to a PC85b and adding extra Game ROMs. - CheshireNoir - 27-09-2021
Thanks Ernest,
PAK5 (And Menu) takes me to what I think is the Database.
Swapping H and I didn't make any difference in getting to the Shell.
I'm wondering if I should burn out a copy of that F ROM onto a 2764 and see if that makes a difference.
I'll try that next.
EDIT: That's not gonna work. F is a 16k EPROM
(I've been out of town for a day, thus the slow responses)
Cheers!
Chesh
RE: Upgrading a Microbee PC85 to a PC85b and adding extra Game ROMs. - Ernest - 28-09-2021
Hi Chesh,
My bad, I should have told you to swap ROMs G & H.
I will need to correct the previous post as I stuffed it up, maybe that is where your confusion is comming in.
The second bank (top 64K are as follows)
ROM E - IC25 Lower = Pak1 - Upper = Pak9
ROM F - IC24 Lower = Pak2 - Upper is reserved for the PC85b MENU
ROM G - IC23 Lower = Pak3 - Upper = Pak11
ROM H - IC22 Lower = Pak4 - Upper = Pak12
ROM I - IC27 Lower = Pak5 - Upper = Pak13
The Upper bank of ROM F is the Menu this is the decoded PAK 10 however cant be directly accessed it will come up with a "Option not Fitted" error in basic. Menu must reside in the upper bank (64K of ROM F it can't be located anywhere else. Normally the lower 64K of the F ROM is the Spreadsheet program.
Shell resides in the lower 64K of ROM I, and must be in this position, this ROM can be called from basic with PAK5.
So in short ROM's F and I can't be swapped with any other ROMs they must remain in those positions and in their respective banks.
Although I have not confirmed it I think that ROM E lower bank must also be in the ROM E position for BASIC's Command Help to function correctly.
Hopefully I have it right this time.
Can you get back to a simple system where you were booting to the shell again?
Ernest
RE: Upgrading a Microbee PC85 to a PC85b and adding extra Game ROMs. - CheshireNoir - 28-09-2021
Hi Ernest,
With the ROMs ordered as per above, it's booting into Shell fine now :-D
Yay!
(Also my replacement speaker arrived so I'll fit that shortly too)
Thanks!
Chesh
RE: Upgrading a Microbee PC85 to a PC85b and adding extra Game ROMs. - Ernest - 28-09-2021
That's great Chesh,
Sorry for the confusion, the order of the alphabetical chip labels and IC# are a little confusing as they don't follow what you expect.
So have you got all the other programs come up as expected in the "Directory" list?
Ernest
RE: Upgrading a Microbee PC85 to a PC85b and adding extra Game ROMs. - CheshireNoir - 29-09-2021
(28-09-2021, 11:20 PM)Ernest Wrote: That's great Chesh,Indeed I have. Most are even identified (Except Kilopede :-D ) correctly.
Sorry for the confusion, the order of the alphabetical chip labels and IC# are a little confusing as they don't follow what you expect.
So have you got all the other programs come up as expected in the "Directory" list?
Ernest
I'm now contemplating swapping out the Viatel ROM for something more "useful", especially as I don't have the video mod for the Viatel modes.
Thanks again!
Chesh