commodore pc-40

[bilbous]

Are the 18 pushed in identical, for the most part to the soldered ones? That would indicate to me a megabyte of ram but the video ram has to live somewhere on the motherboard as well. The 18 soldered would be 512KB of ram.

tms4256-12nl would likely be 4bits wide x 256kbits at 12 nano-seconds. You can search for the chip numbers but most of the relevant information seems to be locked away behind paywalls.

[Elvicat]

erm that computer has a seperate vidoe card, orginaly it proberly had a hercules or something but now it has something beter in it so i think all thouse chips are ram and no the rows dont match except for 1 and 2, the other 2 are different

[evil scotsman]

The tms4256-12nl is a 262144-bit Dynamic Random-access Memory - 120ns,

 the bank of 18 soldered IC's is probably 16xRAM, plus 2 parity IC's, 262144 bits x 16 = 512K RAM.

[Elvicat]

heres a picture of the bios screen but as you can see it dosnt hold much but line 8 and 9 is for memory configs and you set thouse manualy no auto config.

[bilbous]

Another thing that can be helpful is the markings on the substrate itself, it often indicates what is intended to be put in the sockets. It is often cryptic to though.

Does it do a power on memory test?

[Elvicat]

yeah it does a memory test at boot but only up to 640k same as it set to in the bios, if it actually has 1Mb it needs to be set with line 9... havn't figured out how yet tho, and if it's true that there is a jumper that lets you select 512 +512 i wouldnt have any idea what jumper

[bilbous]

Well if it has 1 meg I would think it is line 8 you need to change to 1024.

[Elvicat]

actually line 8 maxes out at 640 and you cant type in your own numbers, theres only a few lines to select from and 640 is the last, maybe theres a switch on the mobo somewhere that makes you use 512 +512 as that page said and i have tried setting both line 8 and 9 to 512 but it didnt like it

[bilbous]

There were add-on cards that you could get to plug into an ISA slot that would test the hardware but it is doubtful you could scare one up now. They came with their own BIOS which took over before the one on the motherboard and boot into the test mode. You should try to identify that drive controller and the other two cards while you are at it. The middle one looks to be isa and could as easily be seated in the bottom slot. Is the top one ISA as well, the placement of the expansion slots seems odd, the middle card is an ISA slot, then a bunch of EISA and a final ISA.
Anyway That drive controller might be able to support an old CD drive on a cable with the hard drive. Then you could possibly use a floppy to boot from a CD. I don't know how that would help though, with your current problem. It might if you found an old test program that wouldn't fit on a floppy.

Sometimes you have to strip down to the motherboard to see what is really going on. There could be significant markings under the power supply or hard drive if haven't looked. Something printed on an empty space, a legend, timings or whatnot. It looks like the motherboard is fairly well annotated.

[Elvicat]

I usualy just call these isa slots 8 and 16bit, the longer is just that anyway 16bit heh, so the long card is 16bit and a westerndigital hdd/fdd controller BUT it won't hande a cd-rom as it's not ide it's eather MFM or RLL type or both, the second small 8bit is a commodore made I/O card with 1 or 2 serial ports, the last card is 16bit and is the graphics card, some paradise i don't really have much clue on this card except it ain't mono like i think the orginal card was, i have a friend that has ahd one of these computers before but it died but i do remember that he said it had a hercules mono card.

[bilbous]

Ok  It was kind of hard to see just looking at the picture. Just to be sure when I said "strip down to the motherboard" I meant remove it from the box and take the expansion cards off, not remove any plugged in chips. If you can get your hands on a 16-bit IDE controller it should work just so long as you have drivers for it. Pretty much any card that matches the bus.

My firewall has a vga herc mono card in it, It works fine and if I could figure how to unpack the X mono driver I could have an actual desktop. It is an 8-bit card.

got to go.

[Elvicat]

i'd rather not touch the mobo as i don't have any replacement parts, i have a tendancy to scr.. up when it comes to stuff thats picky  but i'll see if i find anything around that could be of use

[bilbous]

Getting the system to boot all the required drivers and still have room to do anything can be a real pain. I am not quite sure what you intend to do with that machine if you do get it running. Those QUE books "Upgrading and Repairing PC's" are pretty detailed and if you could get a hold of an early version -- I quoted an 8th edition, from when pentiums started to come out -- you might find it useful.

[Elvicat]

well it's up and booting just fine atm, with some small quirks but thats expected, the main part is that it's actually working and can be used if you wish as from what i gather this comp and to usual that's why i've spent so much time on it heh

the only thing that boughles me still is that ram prolly will figure it out sometime just dont have a clue what to look at atm but maybe ill notice something, i can't even fasten the harddrive to the case eather atm as i'm missing some parts

[bilbous]

You could stick a network card in it and use it as a network client. I suppose if you had a lot of software for it you could do stuff, as people did stuff with it when it was new. Was there anything special about the commodore PC?  You are using dos so I cannot think what it might be.

As for the ram there might be a dip switch on the motherboard underneath the power supply unless you looked.