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XT board questions (FT SUPER-640 )

lucasdaytona

lucasdaytona

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Jul 23, 2011
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Brasil
Hello!

I've got a strange board, something like this , made in Taiwan, no Serial Number, and I have some questions:

1) The bank 0 and 1 are empty, while the bank 2 and 3 are full (M5K4164ANP), according to stason, I should full populate bank 0 and 1 with 41256 CIs to get 640KB right?

2)What is the point of having so many ROM slots empty ? There are seven ROM slots, only ROM7 having a ROM (looks like the BIOS). Long time ago, I had a xt laptop, and DOS was in a ROM, this could work the same way here?

3)I'm very new to these XT boards, the power supply connector is a bit strange, the same 12 pins from a 286/386/486/AT class, but a different shape, a 486 Power supply will fit, but will work? Also, this board have an extra 8 pin connector, same style, side by side with the 12 pin power connector, what is this?

4)The board don't have a CPU, what should I use?

Thanks to all!

This board price is the most fun part... just 0.99 USD.

Regards,

Lucas
 
1) Yes
2) In these boards, ROM sockets are mapped in the F0000-FFFFF area. Each socket accepts a 27C64 EPROM, so you can put ROM extensions in them. The most common is the IBM Cassette Basic (it uses four 27C64 chips)
3)No idea about that extra connector. Can you upload a picture?
4) You can put a 8088 or a Nec V20.
 
That 8-pin connector is a power connector for an alternate PSU common in the Far East. You can ignore it.

I probably have the twin to your board. I have only one of the BIOS ROM sockets populated.
 
Chuck(G) said:
That 8-pin connector is a power connector for an alternate PSU common in the Far East. You can ignore it.

I probably have the twin to your board. I have only one of the BIOS ROM sockets populated.
Click to expand...

I though you had sold your board! There's a old post here about you selling it... ;)

by the way, this is a Turbo board?
 
Never found anyone interested, so I stuck it in a case and am using it now, as well another different XT clone.

Mine is slightly different in that there's no header for a reset button. All of these boards were based on a Taiwan ERSO reference design, so they're very very similar.

Yes, it's a turbo. You can use keyboard Ctrl-Alt-keypad "-" to switch if you don't use the hardware switch--the cursor changes shape when you do this. I run mine with a V20.

I imagine that you're missing the 41256 DRAM because they could be carried over to a 286 or 386 motherboard--and memory was expensive back then.
 
thanks for the info! You're probably right about the memory... I also have a 286 board that don't have a single memory chip... looks like I will have to buy a lot of chips.

Do you think it is possible to put DOS on a ROM and use on this board? I've seen a DOS 6.2 ROM somewhere on the net...
 
I don't know--perhaps. It might take some code manipulation to do. Perhaps one of our Tandy 1000-series users could contribute an image (there were other machines that used DOS in ROM as well, including HP and Sharp).
 
Chuck(G) said:
I don't know--perhaps. It might take some code manipulation to do. Perhaps one of our Tandy 1000-series users could contribute an image (there were other machines that used DOS in ROM as well, including HP and Sharp).
Click to expand...

Man, now I'm scared! Is the first time that I see one "I don't know" coming from you :(.

The problem is that I don't understand how those things boot, anyone can tell me a book to understand this?

I think will be much easier buy a XT-IDE (I don't have a 360KB drive here, only 1.2MB).
But the ideia of using DOS in a ROM is very interesting to me!
 
It is complex and requires a lot of low level BIOS programming. The IBM PS/1 model 2011 has a 128 kb ROM drive with the system boot files.
 
Nope, just as long as it's rated for the same speed--I don't know if these old boards provided for "split speed" operation. But an Intel 8087 will work with an 8088 or V20.
 
Chuck(G) said:
Sure--it's the actual clock frequency that determines how fast a CPU runs; it's not the frequency stamped on the package.
Click to expand...


Hum, sorry, but I did not get it... maybe I'm not reading right. Could you please explain this with a example or two? I usually read very well in english, but sometimes I get some trouble... thanks!
 
Suppose you have an 8088-2, which is rated for 8MHz. Can you run it at 5MHz or 3MHz? Certainly! It won't run any faster than a standard 8088 at those frequencies, even though it is a chip rated at 8MHz.

You might call it under-clocking.

As an interesting unrelated tidbit, I run a 5MHz V20 at 8MHz with no problem (i.e. it doesn't fail and there's no overheating).
 
Chuck(G) said:
Suppose you have an 8088-2, which is rated for 8MHz. Can you run it at 5MHz or 3MHz? Certainly! It won't run any faster than a standard 8088 at those frequencies, even though it is a chip rated at 8MHz.

You might call it under-clocking.

As an interesting unrelated tidbit, I run a 5MHz V20 at 8MHz with no problem (i.e. it doesn't fail and there's no overheating).
Click to expand...


Ok! Thanks for the help. I'm very hopeful now.

Now it's time to buy some things!

When the system is done, I will post some pics.

Thanks to everyone.
 
The board doesn't works! Fan spins, the beyboard blinks one time, and the speaker says a small "buzz" and then nothing else happens. Maybe a dead 8088? And, stason says the cpu should be in U4, what is very strange to me. At this time, the 8088 is installed in the U3 socket.

any clues?
 
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