Parallel port boot & a DOS cassette tape interface for the 5150/PCjr

[deanimator]

Hi everyone,

For the benefit of other fans of vintage x86 machines, I've developed a ROM code that enables you to boot from a parallel port, by means of a cross-over parallel cable and a machine that provides a bootable image (currently DOS or Windows). I use this in my 5150, if there's no bootable drive before the ROM-BASIC loads. But it can also be used in other, "more modern" x86 systems, e.g. when placed inside the BIOS, or in a boot ROM socket of a network card etc.

And, if there's anyone that'd like to breathe in some life into the cassette port of a 5150 or a PCjr, I came up with a small application interface that can be used inside PC-DOS or MS-DOS to access the tape from there, since DOS had no native support for this. Ofc you don't need to use a tape recorder; any audio device with a mic or line-in and a PC with DOS shall work.

Both of these experimental apps are released as open source.

Comments, hints and suggestions appreciated.

Regards

 

[mbbrutman]

That is neat! Definitely will check it out ... (both projects).


Mike

 

[krebizfan]

Great proof of concept.

 

[Eudimorphodon]

Do you know if the "option ROM" version of the parallel port boot software will get along with the XTIDE bios boot menu? I'm curious to try this, although I'll have to build a laplink cable adapter for my Tandy 1000 and jumper the parallel port into 5-bit mode. Presumably I could pad an XTIDE BIOS image with this at the next 2k boundary and flash it. (XTIDE only occupies 8k of the 32k available in the flash on my card.)

 

[deanimator]

The actual code size is a little bit below 2k, so that shouldn't be a problem with a little bit of tweaking.
The "5150-optimized" variant of the LPT booter, hooks INT 18h by default. So even if you had 2 chips in your system, one with XTIDE and the other with the LPT boot (in different memory locations), you could add in a new boot menu entry to XTIDE just to execute INT 18h.

That at least is the theory

 

[chris_nh]

Awesome!

 

[Shadow Lord]

Hi everyone,

For the benefit of other fans of vintage x86 machines, I've developed a ROM code that enables you to boot from a parallel port, by means of a cross-over parallel cable and a machine that provides a bootable image (currently DOS or Windows). I use this in my 5150, if there's no bootable drive before the ROM-BASIC loads. But it can also be used in other, "more modern" x86 systems, e.g. when placed inside the BIOS, or in a boot ROM socket of a network card etc.

Very cool and very reminiscent of ADTpro on the Apple.

 

[Shadow Lord]

Very cool and very reminiscent of ADTpro on the Apple.

I stand corrected. While the idea is the same. This does require a bit of HW magic (i.e. the BIOS chip in a NIC for example) to make it work. However, very cool still!

 

[deanimator]

Yes, it's a tiny bit different, but a part of the idea (sending a disk image over a parallel interface) can be reminiscent.

In DOS, you could read or write a disk image/binary file using PARTCOPY and send it over a serial or parallel interface with the classic INTERLNK/INTERSVR combo, or even with Norton Commander and such.