VOGONS


First post, by Kubik

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Folks, I have purchased relatively cheap Tandon 7488, that was sold as non-functional. First, it was obvious it won't work as it had no memory which was clearly visible on eBay picture - that's why I decided to buy it, hoping it might be relatively easy to fix. However, after the thing arrived, it turned out it misses more than just RAM. The CPU is missing as well 😀
Now for the fun part - what CPU is actually supposed to go there? 😀

The mainboard consist of two boards, in fact. The bottom board has PLCC-68 socket that looks like being meant for numeric coprocessor. The upper, smaller board (with a number of PALs) has traditional PGA-168 socket, which suggests 486.
There are some oscillators missing on the board as well, including one empty DIL-14 socket. That makes me nervous as well...

Before experimenting with this stuff: is there any Tandon owner who could shed a bit more light on this strange beast?

Reply 1 of 2, by Kubik

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Some experiments and advanced googling revealed that this is actually an 386SX machine with Tandon's proprietary add-on board for 486. I've plugged in an 486DX2 / 66 and the computer sprung to life.
Some facts:
- entering setup via Ctrl-Alt-Esc
- despite using 486 processor (on the add-on board), it actually works with just two 30pin SIMMs 😀 Of course, it's basically an 386SX, and that 486 CPU is crippled to use 16bit bus
- hard drive table in BIOS doesn't seem to be the same as PS/2 one. The BIOS doesn't support autodetecting or user entry for CHS, thus you have to go through all 47 disk types, and find the best match for your drive. That also means that bigger drives won't be supported (at least without OnTrack or other drive manager)

Reply 2 of 2, by GuillermoXT

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I have a TM7521 also called as Target 40 but its a 286 ^^
Did you get the board running @Kubik ?

My Retrosystems:
K6-2 400 running Win98SE
P1-133 with Win3.11
Tandon 286-8MHZ Running DOS 5.0 on XT-IDE Card