1 Topic by bushy555 (edited by bushy555 2024-08-29 05:51:08)

  • From: Australia
  • Registered: 2019-04-18
  • Posts: 78

Topic: TRS80 model 1-3

Very early days, (only started this afternoon), but have managed to get Huby, Lyndon Sharp and one of Tim Follins engine playing ok in one of the TRS80 Model 1 emulators. Writing out to the cassette port, and a few emulators will emulator the port to the speaker.  Apparently with real hardware you just connect an amplified speaker to the cassette 'out' jack.

Assemble to a .CMD file, which has an eight byte header - of which I'm still to find the specifics on.
Using a special TRS80 'Z80asm.exe' assembler, it spits out the binary directly to a .CMD file with this specific header.  I'll eventually find the info and chuck it into the source for Pasmo and SJASM.
Biggest drama with this z80asm.exe assembler is that is doesn't accept hex as $THIS or #THAT. Everything has to be THISh.

Details:

ORG $6000
Cassette port hangs off Bits 0 and 1 on port 255.
Output: Bits 0-1: 00=0.85 Volts, 10=0.0 Volts, 01 = 0.46 Volts
So... spit out values $00 and $02 to OUT ($FF)

Lyndon89 engine (I think), "mental" tune was the simplest and so far the best sounding; didn't even need to touch anything with the speed. Jut worked. And this is with the model 1 running at , what 1.8 Mhz or so.
I'll continue to play with this for the next few weeks to see how many engines and tunes I can get running ok.

  • utz
  • utz
  • Administrator
  • Offline
  • Registered: 2015-06-28
  • Posts: 1,022

Re: TRS80 model 1-3

I have some faint memories of The Invisible Man having written a custom driver for the TRS-80. I also have a pile of old music editors on my hd, don't think I ever actually tried any of them though yikes

bushy555 wrote:

Output: Bits 0-1: 00=0.85 Volts, 10=0.0 Volts, 01 = 0.46 Volts

So that thing actually has 3 volume levels! That could be interesting to explore. Though I wonder why the voltages are so low overall. Doesn't the Speccy output something like -5V?

website | bintracker | github | bandcamp | soundcloud

utz's Website