💾 Archived View for uscoffings.net › retro-computing › systems › Tandy › t › txcadd.txt captured on 2023-01-29 at 05:49:11.
⬅️ Previous capture (2022-06-04)
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I use a Tandy 1000TX at work set up as a low-cost CADD system. It's not blindingly fast (see the comparitive times later in this message), but works pretty well. I have the following items installed: Everex 2400 baud internal modem set to COM1 (IRQ4) Logitech Ergonomic Serial Mouse using the built in serial port, set to COM2 (IRQ3) A Tandy hardcard where I replaced the controller with an OMTI 5527T and reformatted to 32 megs - drive is a Miniscribe 8438 Set motherboard dip switch #2 to OFF, and the controller automatically configures itself to IRQ5, and can co-exist on IRQ5 with the internal video (if you use it). A MicroMainframe 5150T EMS board populated to 2 megs with 100 nano-second chips. You don't need chips this fast, I just stumbled accross them at a time when no-one had any chips available. I've never used more than 736K at once, although I just bought a new program that recommends a 1 meg ram disk. The EMS board does not use a hardware interrupt. An Everex EV657-1 super EGA video board. This board supports 640 x 350, 640 x 480, and 800 x 600, all at 16 colors, but does not support the other VGA modes. You have to run a memory resident utility to get 640 x 480, and 800 x 600 requires program specific drivers. This is the mode I use with Generic Cadd Level 3. This board is set to the non- maskable interrupt (NMI). Turn motherboard switch #1 to OFF when using an EGA or VGA board. The Hercules emulation is set to OFF on the board, and it auto-switches between the three hi-rez modes without any problems. The Everex board also has a parallel port on it. I have the parallel port set to address 0278-027F, and IRQ7. Also turn off motherboard switch #4, and the system will allow the normal printer port to function as PRN or LPT1, and the second port on the video board to function as LPT2, with both of them operating on IRQ7. The Everex board's parallel port drives a Roland DXY990 11" x 17" plotter I bought through mail order three weeks ago on closeout. A Microway 287-12 turbo coprocessor. This is a math chip and clock circuitry to run the 80287 at 12 mhz, whereas the normal circuitry runs the math chip at 5.33 mhz. I built a small relocation board because this 287 turbo didn't clear my hardcard. My monitor is an NEC MultiSync II (not the 2a). The controls are all right up front, and they allow you to expand the disply right out to the edges of the bezel. I'm very happy with it. The 1000TX has a small quirk when used with some EGA and VGA cards. It seems that pressing control-alt-delete on most machines cause a so-called "warm boot", where the system bypasses the memory checks (much quicker). The 1000TX on the other hand does a "cold boot" where it includes the memory check. Hitting control-alt-delete confuses the video card, and you don't get a reliable reset. There is a set of two TSR's, in a file called RB1000.arc, in one of the DL's here, that neatly fixes this by using the right shift key and the print key to do a real warm boot on the TX. (The left shift and print keys still do a print screen.) It works, and the video card doesn't get confused, and it's quicker than control-alt-delete. I also run two TSR's to boost speed: Rambios.arc: This utility relocates the video board BIOS code into RAM. I downloaded it from the Everex bulletin board @ (415) 683-2984. Qfresh.com: This is the utlity generated by a program that analyzes and resets the memory chip refresh rate (CALCQF.arc). It has no measurable effect on the Cadd program screen redraws, but other commands run perceptably faster, including speeding up hard drive access. Be careful, as this program drives bus mice crazy, changing the resolution, but serial mice are unaffected. Save your money on the video upgrade. If you put in an EGA or VGA card, you have to put the jumper back in to avoid a memory address conflict between the video upgrade and the memory on the video board. Installing the EGA or VGA board dis-arms the internal video (along with turning motherboard switch #1 to OFF), and gives you your full 640K of base memory. Find and run a program called Thrasher (THRASH.arc). It measures the optimum setting for the Buffers command in you config.sys file. This dramatically speeds up disk access without the conflict potential of many disk caching programs. Mine is set to Buffers=20. Last, make sure that you load enough TSR's, and config.sys commands so that your free memory is no more than 592K. Use CHKDSK.com (a DOS command) to verify this. I ran into a problem with Generic Cadd and the Micro-Mainframe EMS driver, conflicting with the Tandy BIOS. It seems that if you have more base memory available than 592K, the programs can't locate the EMS properly. I found this when I first got the EMS board, and Generic CADD reported 65,000 bytes available for drawing memory, instead of the 2 megs I just installed. It seems that at the time the EMS board was designed, they didn't allow for EGA cards or video expansion in the 1000'S and assumed that at least 16K for video and 47K for DOS would always be used. This along with the EMS driver brought the maximum leftover memory down to 592K or so. Comparitive times to do a zoom all command in Generic Cadd on a test drawing: TX without co-processor 55.2 seconds TX with co-processor @ 5.33 Mhz 16.4 seconds TX with Turbo 287-12 13.2 seconds Compuadd 386-20 - no co-pro 19.7 seconds Tandy 4000LX with co-pro 4.4 seconds 800 x 600 takes about 0.2 seconds longer than 640 x 480. Whew!