root@techsup (12/27/85)
A few comments & corrections reguarding the Tandy 1000 /* Written 7:40 pm Dec 22, 1985 by moncol.UU!john in techsup:net.micro.trs- */ >> >>Tandy 1000 >>========== >>RE: its compatibily, It is quite compatible up to a point: I have >>found that several games fail to start up (the original version of the >>diskette) which indicates problems with the floppy disk controller. I >>looked at the schematic diagrams of the t1000 and the XT controller >>and they are quite different - the Tandy uses a couple of PAL's and >>large devices while the XT controller uses a lot of TTL MSI. Not >>having a hardware ref manual for t1000, I don't know if the t1000 >>emulates the XT controller to a high degree but I doubt it. > >The Tandy 1000 uses an Intel 8272A FDC. Doesn't the IBM use an NEC chip? The 8272A and the upd765 are pin & software compatable. When i asked Intel for more detailed data on the 8272A they said they had a license agreement with NEC and to contact them. A bigger difference is that the base 1000 does not have a DMA for use with the FDC. If expects to talk to the FDC using a DMA it will have a problem (Adding a RAM/DMA board fixes that!). >>The machine is a cross between the PC and the jr. One BIG compat. problem >>has to do with DMA. The base machine has none, but the memory cards add >>DMA circuitry. The as a result, you can not use any add-in cards with >>memory unless you have first added a tandy memory card. since the machine >>only has 3 slots, this is a pain (tandy has no multi-function card for >>this beast last time I checked.) > >Tandy now produces a card called the MEMORY PLUS card which will allow >expansion to 640k using only one board (it used to take two Tandy boards) >and will take a piggyback RS232 or clock/mouse card. > >-------------------------------------------------------------------------- >Now for the $640 question... assuming that there is no problem with the >power supply, will an IBM PC-compatable hard disk and controller work in >the 1000? > >Since the 1000 is an IBM-compatable, one would think so. A note in the >current 80-Micro, however, seems to indicate that a special ROM on the >controller board would be needed. > >Anybody know for sure? /* End of text from techsup:net.micro.trs- */ Hard disk controllers usually use INT5, which is used for a verticle sync/timer interrupt on the 1000. A different interrupt would have to be used with a ROM that was aware of it. Both Tandy & 'other' vendors sell controllers made for the 1000 (See 80-microcomputing magazine for some of the others. Make sure it is for the 1000 or be ready to modify its rom and board!). A note, the newer Tandy 1000's (25-1000A), has a socket for the 8087. The older ones (25-1000), do not. Gary Kueck trsvax!techsup!root Radio Shack Technical Support #0220 (817) 338-2288