My Compact Flash CF8 Microbee

[ChickenMan]

I finally got my CF8 Compact Flash updated Premium 128k Microbee out to test it out.  To my surprise it fired up straight away.

   

Problem is I only have the one CF card that boots and I dont have the facilities to make further images nor able to find/buy any CF cards with the same CHS layout.  Plug in a Gotek, which is seen as E: drive, and copy files across to one of the 4 x 5mb partitions of the CF.  Currently B: is full (well partly) of games

A few of the keys dont work even after giving them a good wiggle, so thats a job for another day.

[Matty72]

ChickenMan, I did the CF mod.to.my 128k Prem years ago and it worked well when it worked, then would occasionally corrupt the CF card whereby I'd have to redo it all. I'm aware that some mods to bios were done over time to address this and from memory the lates version only made my situation worse.

My questions to you (or others who helped get this all working) are:
A) Is CF Rdy/Bsy pin 37 being used? (CF ready to Z80 interrupt, or other?)
B) Is CF wait/IORdy pin 42 being used? (CF wait to Z80 wait)
C) Does MBee bios do any pre-write read as a check that the CF card is indeed ready to be written to, or does it solely rely on above signal(s)?
D) Does the bios command the CF card with Ox01 parameter thereby placing it into 8 bit IDE mode, or does the CF Mod attempt an 8 bit mode by holding specific pins either high or low (i've read there's two 8 bit modes possible, memory mapped and IDE. I assume MBee goes for 8 bit true IDE mode ?).

I ask such questions as when i finally get back to my Bee, i want CF to work reliably and expect your reply to be of help.

Thanks.

[Graham72]

Interesting thread. Chickenman do you know the CHS layout? Is the connector IDE compatible? I see Amazon sells a 32MB "industrial card" which is happy in old school digital cameras.

[greybeard]

It was I who dun it.
The original discussions were lost when the old beeboard? forum shutdown. Discussion then moved to MSPP forum where the was some further updates done. The most recent were in the last year or so. Basically the ide 8 bit mode is selected for the cf. I had issues originally with it being fussy with regard to which cf would and wouldn't work.
Over the years others have used a similar technique and investigated it further. Search for 'rc2014' info on the internet and they researched the issues further. Some circuity changes helped but it is still a bit fussy with regard to cf's. Also search MSPP for a couple of threads on there about the CF interface.
I've updated my coreboard with some updates (see MSPP for details).
I've also designed a usb interface that allows you to r/w a fat32 formatted usb stick to use for xfers to/from pc/mbee, very handy to move data/files between systems.

re corrupting the cf, I believe that the issue was related to a bug in the bootrom/bios and have been fixed and/or reduced. The actual changes for the cf interface was pretty trivial, just selecting 8 bit ide and that was about it. I'll try and dig out a bit more and/or locate the references online.
Some early stuff is here https://sages.com.au/wordpress/?p=79 (sorry some of the referenced links don't work anymore).
cheers
Rod aka greybeard

[ChickenMan]

I ask such questions as when i finally get back to my Bee, i want CF to work reliably and expect your reply to be of help.

Thanks. Not sure if I'm going to be to helpful as I really cant answer your A), B) etc questions, I'll leave that to Greybeard.

I found generating the cfboot_0_59_cf8_128k_1p_CHS_490_4_32.hdd-76-4-32 (for example) selecting the matching BIOS rom and most importantly the actual CF card itself all can effect the read/write performance. I found the Sandisk 32MB CF that have CHS of 490/4/32 to work without issues on all my CF Mbee's that I had.

I dont have that 'bee in the top pic any more, I started with just the simple and cheap IDE to CF cards and a few wires actually worked better for me. But I dont have those units either anymore.  I use a Suzy CF 0.4 version that has been upgraded to 0.5 and I can now use those cheap no-name CF cards from China as in this pic.  Only issue I found is if I use ubee512 to write files to the CF card image then that image would not boot in the Mbee when written to a CF card. So all files were transferred via a Gotek (or external 3.5" floppy drive) plugged into the Mbee without any issues.

   

Also, when generation the cfboot image that it also creates the 3 main Mbee floppy bootable images, I found ONLY the SS80 image to actually work.  You can boot it if you hold down the F key when you turn the Mbee on.

[Matty72]

Thanks guys, so it sounds like there's hi confidence with latest firmware(s) and hardware.

I wired mine up per a .pdf in the repository (direct connects, no logic ics) and used PB? BIOS (from memory). I had two resisters added to the cf adapter i guess holding a couple of pins high (from general research at the time).

I broke the wiring while.messing about some years back and bought a cf pcd that connects to the 50 way port that a forum member had created but life got in the way so it's never been tested.

I'll look into what hardware changes Suzy has done and start again from there.

I'll look into the USB option as well, sound great. I assume there a specific bios for that (i'll do some reading).

Appreciate the help.

[greybeard]

The usb option uses a cheap interface board from aliexpress with a ch376 chip but it only works with a small program running on the bee for file transfer. It doesn't require any bios mods and it was never integrated into cpm.

Most of the info is available here.... https://www.microbee-mspp.org/forum/viewforum.php?f=87