PDA

View Full Version : Multifunction card - floppy/ram/serial?



PhilipA
February 18th, 2016, 06:59 PM
All,

I'm looking to make space inside my Compaq Portable, which has only a few expansion slots.

Currently I have the Compaq CGA card, a single-density floppy controller, Ethernet card, Lo-Tech IDE-CF and a Diamond Flower MPF-1 multifuction card.

The Multi-function card is great, it has a clock, two serial ports, a parallel, 384kb of RAM and a game port (if memory serves, I don't use all of, it, mostly just the clock, RAM and serial port).

I'd love to free up a slot by removing the floppy controller, but does anybody know of an 8-bit multifunction card that has base RAM extension, floppy controller and serial port as the minimum features?

Thanks


--Phil

vwestlife
February 19th, 2016, 04:17 PM
I've never seen such a thing. On a PC/XT class system without the full 640K RAM on the motherboard, you always end up with at least two cards installed:

1. floppy card
2. serial + parallel + game + RAM expansion card (such as the AST SixPack Plus)

or...

1. floppy + serial + parallel + game card (such as the Chaplet 7-Plus)
2. RAM expansion card

PhilipA
February 19th, 2016, 05:54 PM
Hm. Well, that's unfortunate. I guess that's the price you pay for a form factor. (The Compaq Portable!)

I didn't think to see if it would boot without the floppy card installed...


--Phil

jh1523
February 24th, 2016, 07:34 AM
You could free up a slot by consolidating the floppy and XT-IDE cards into one card. Use a 16-bit (trial and error, some work some don't) ISA IDE+floppy card, and stick the XTIDE universal bios as well as a FDD bios in an EPROM somewhere at F000, F200 or F400 (may require making a custom BIOS chip)

I've done something similar in my XT clone, see thread http://www.vcfed.org/forum/showthread.php?48479-XT-clone-built-from-ebay-components (somewhere on page 3 or 4)

PhilipA
February 29th, 2016, 08:24 AM
You could free up a slot by consolidating the floppy and XT-IDE cards into one card. Use a 16-bit (trial and error, some work some don't) ISA IDE+floppy card, and stick the XTIDE universal bios as well as a FDD bios in an EPROM somewhere at F000, F200 or F400 (may require making a custom BIOS chip)

I've done something similar in my XT clone, see thread http://www.vcfed.org/forum/showthread.php?48479-XT-clone-built-from-ebay-components (somewhere on page 3 or 4)

That's a thought.. I have a 16-bit card floating about.. I'm not sure if the IDE portion of it works in an 8-bit slot though.

Not that it helps greatly, I soldered the IDE pins to the CF adapter to the XT-IDE board...

I'll have to explore that avenue, though I don't hve any hardware that is specifically set up to burn ROMs. I've only written some PICs with a circuit that used a couple Zeners and the CTS/RTS lines of an RS-232 port.. I've dug about a bit using my Arduino to read ROM chips.

I'll have to see if what I have even wants to work. Now you've got me thinking.


--Phil

jh1523
February 29th, 2016, 08:53 AM
You can get CF/IDE adapters on ebay for a couple of bucks. And I'm sure there are people around who would be happy to burn custom eproms for you (I know I'm one).

PhilipA
March 1st, 2016, 01:59 PM
I had a rummage in my box of bits. I have 2 IDE/Floppy/(serial, game) adapters, both of which have no BIOS DIL socket.

The IDE-CF adapter I have was fairly cheap... Amazon, I think. I can get another without too much hassle. I'll have to see if I can source a suitable IDE/Floppy board. Any recommendations based upon your experiences?


--Phil

jh1523
March 2nd, 2016, 03:20 AM
IIRC I had better luck with UMC-based cards. I may be wrong though, and it's not based on a huge sample (I tested about 6 or 7 cards, and some had clearly ISA contact issues as they would work when some pressure was exerted down on the card but not when let free).

The multi-IO cards don't typically have eprom slots, they rely on the code being part of the motherboard BIOS. My XT board had empty EPROM sockets mapped in the BIOS area, and I used those to add extensions. You can use a socket on a NIC, but those are typically mapped in the UMB area not the BIOS, and that may be a problem if you plan to add RAM in the UMBs.

I don't know if the Compaq Portable has any unused EPROM sockets on the motherboard. But typically you can overcome this by replacing the BIOS chip with a custom made one that has both the original BIOS code and the extensions burned in the same chip. That's because the BIOS code doesn't take all of the 64k of the BIOS area.

PhilipA
March 2nd, 2016, 09:12 AM
It's been such a while since I've done anything I'd forgotten that was a possibility. There might be a socket on the board, I'll have to check- possibly for BASIC. I'll pop the lid off it when I have time and check see.

EDIT: Looking at Google images, it would appear there are a number of spaces on the board for extra ROMs. A couple socket spaces on the ones I've seen appear to be present but unsoldered.

I don't have a manual to see what's specified for what.


--Phil


IIRC I had better luck with UMC-based cards. I may be wrong though, and it's not based on a huge sample (I tested about 6 or 7 cards, and some had clearly ISA contact issues as they would work when some pressure was exerted down on the card but not when let free).

The multi-IO cards don't typically have eprom slots, they rely on the code being part of the motherboard BIOS. My XT board had empty EPROM sockets mapped in the BIOS area, and I used those to add extensions. You can use a socket on a NIC, but those are typically mapped in the UMB area not the BIOS, and that may be a problem if you plan to add RAM in the UMBs.

I don't know if the Compaq Portable has any unused EPROM sockets on the motherboard. But typically you can overcome this by replacing the BIOS chip with a custom made one that has both the original BIOS code and the extensions burned in the same chip. That's because the BIOS code doesn't take all of the 64k of the BIOS area.

PhilipA
March 13th, 2016, 06:36 AM
Ok, so I'm getting a bit of time in to be able to think about this again.

Does anybody have a service manual that identifies each spare socket location in the row next to the BIOS?

Thanks

Phil

jh1523
March 13th, 2016, 01:49 PM
There's one at http://minuszerodegrees.net/manuals/Compaq%20Portable_Plus_286%20-%20Maintenance%20and%20Service%20Guide.pdf (it covers several models, including the original portable). But it doesn't seem to have info about the sockets in question.

You could plug eproms with known content in them, then dump the memory and see where they are mapped.

PhilipA
March 14th, 2016, 02:17 PM
I would but I don't have any EPROMs other than the xt-ide one and I'm not sure that's the right type.

Phil