Free-dos customised for Master 512

[mbernardi]

Given that the currently available Dos Plus doesn't have extensive MS-DOS compatibility, how difficult would it be to customise FreeDos to run on the Master / PiTubeDirect?, and once that was done, adding a 386 co-processor to PiTube?

[danielj]

It's not that DOS-plus isn't very msdos compatible, it's that the hardware isn't completely IBM-PC compatible. Porting freedos won't fix this.

[vela025]

Given that the currently available Dos Plus doesn't have extensive MS-DOS compatibility, how difficult would it be to customise FreeDos to run on the Master / PiTubeDirect?, and once that was done, adding a 386 co-processor to PiTube?

It takes a while but the current freedos floppy image from the freedos website boots using pitubedirect, however it cannot "see" the hard disk. Using the method linked in my top post here https://www.stardot.org.uk/forums/viewtopic.php?t=21288

[vexorg]

Just curious, what dos programs do you want to run on the master that you cant run on a cheap PC?

[mbernardi]

It's not that I can't run it on a cheap or virtual pc. It that it would be cool to run it on a beeb.

[vexorg]

I've never quite seen the point of the pc part, the memory and video limitation make it almost pointless.
I thought there may be something specific that needs the hardware.

[mbernardi]

Well originally the 512 co-pro was slightly cheaper (and the Master 512 was smaller) than the PCs available at the time. Also some of us didn't have space for another large computer. It's just that Acorn's implementation was not well done.

How would I do it now? Use a 286 or 386 processor not 186, include a bios to interface between pc and Beeb. Use FreeDos as OS.

[danielj]

I've never quite seen the point of the pc part, the memory and video limitation make it almost pointless.
I thought there may be something specific that needs the hardware.

That's not really fair - it would run text mode applications (such as word processors and databases) quite effectively and didn't make an awful fist of CGA. GEM applications would also run fine. There was also the pc-plus which took RAM to 1MB and made it much more useful. It really depended on your use cases.

d.

[mbernardi]

And as I said previously IBM PC compatible machines were horrendously expensive and bulky. A BBC Master with internal co-pro was cheaper and smaller (even with double floppy drives).

[paulb]

Well originally the 512 co-pro was slightly cheaper (and the Master 512 was smaller) than the PCs available at the time. Also some of us didn't have space for another large computer. It's just that Acorn's implementation was not well done.

It was an interesting idea in principle: augment the Beeb to allow it to run PC software and provide a low-cost, incremental path into acquiring a PC-compatible. And it is one of those things that seems reasonable on the face of it: you only need to add an additional component to an existing system and that saves you buying a completely new system.

Unfortunately, it suffered from some of the same economic obstacles as the Z80 Second Processor did with regard to that expansion providing genuine CP/M compatibility. In that case, CP/M really needed you to have disk drives, which added considerable expense in the first half of the 1980s, but up to a certain point in time, one could argue that generic CP/M machines were still more expensive and had poorer capabilities. Torch's Z80-based systems and expansions slid into this niche while it lasted, providing the arguably superior Beeb graphics and sound plus a workspace for programs somewhat larger than that normally available in many CP/M systems.

Similarly, with the Master 512, anyone wanting to run DOS software would have needed at least one disk drive, but by the time of the Master series, double-sided 80-track drives were a bit more reasonably priced. However, just as disk drives fell in price, related economic factors pushed down the pricing of PC-compatibles. Since the Master 512 card was £500 to start with, reduced quickly to £400, and only later discounted to far more reasonable prices, the total system cost was not especially competitive.

Then there were all the compatibility and performance issues. Torch had a crack at this kind of expansion with the Graduate and pretty much illuminated the likely issues, such as the Beeb video system not really keeping up with PC scene, and so you can read complaints about a lack of colours in 80-column modes where the PC is able to use its character generator instead of a bitmap mode. If Acorn had evolved the Master graphical capabilities just slightly, as discussed previously, that would have been less of an issue even by providing a four-colour 32K 80x25 "text" mode, for instance.

Compared to something like the Advance 86, which was introduced when disk drives and memory were pricey, where one might have bought the low-cost model and then upgraded, the Master 512 and Graduate approaches did at least provide a more viable upgrade path by building on a well-supported platform with a sizeable back catalogue of tape software. In contrast, the Advance 86 Model A was a weird, PCjr-like system that probably had orders of magnitude less support than even the PCjr. So, Acorn's approach was reasonable, if largely appealing to the company's existing users.

How would I do it now? Use a 286 or 386 processor not 186, include a bios to interface between pc and Beeb. Use FreeDos as OS.

When Acorn first had a go at making a PC-compatible system - the ABC 300 series - competitors in the same class were also going to be several thousand pounds, and so they went for a higher end approach involving the 286, ostensibly to support Concurrent DOS. Keeping that solution might have mitigated compatibility issues somewhat because solutions like Merge, featuring on the AT&T PC 6300 Plus, permitted DOS program virtualisation with only a modest performance penalty. That might have overcome many of the compatibility issues.

Why Acorn went for the 186 is a minor mystery but it could have been related to power consumption, and I think the 186 was mostly aimed at, or successful in, embedded applications. When there was a PC podule planned for the Archimedes in its early days, Acorn suggested the 286 for that, but eventually decided that the product wasn't worth bringing to market. Eventually, as we know, the PC expansion card regularly featured in Acorn's ARM-based line-up, leading to the Risc PC and its compromised "dual-architecture" capabilities that also had a similar level of appeal to purchasers.

With all this said, however, I can understand the enthusiasm for the Master 512, and nobody really needs to justify doing whatever they like with it. That is largely what we are here for, after all.

[vexorg]

But it's not 1984 now, so why do it now?
What programs do you need to run on the master 512, what will it achieve over a cheap PC/laptop that we all have sitting around probably doing nothing?

[SKS1]

If you enjoy doing it, do it. Just don't expect people to drop their own interesting development to do yours.

[mbernardi]

Because I can

[vexorg]

I'm not saying stop, just wondering why?

[mbernardi]

I'm not saying stop, just wondering why?

Because I can, because it's cool, because why not.

[jgharston]

Just curious, what dos programs do you want to run on the master that you cant run on a cheap PC?

Programs that can access the Econet server, access the Beeb's sound and graphics systems?

Edit: There's a "M512 Compatibility Enhancer" that improves the DRDOS system and improves compatibility with various things. Have you tried that to get your goal of improved functionality. (Sorry, I can't remember what it's called and a few minute's Googling hasn't helped.)

[james]

Edit: There's a "M512 Compatibility Enhancer" that improves the DRDOS system and improves compatibility with various things. Have you tried that to get your goal of improved functionality. (Sorry, I can't remember what it's called and a few minute's Googling hasn't helped.)

Is it the PC Compatibility Enhancer (aka PCCEj? If so, there looks to be a copy on 8BS disc 512-3-1 (BBC PD 512)

Edit: and apparently pages of M512 information at http://www.cowsarenotpurple.co.uk/bbcco ... tware.html

[vela025]

Edit: There's a "M512 Compatibility Enhancer" that improves the DRDOS system and improves compatibility with various things. Have you tried that to get your goal of improved functionality. (Sorry, I can't remember what it's called and a few minute's Googling hasn't helped.)

Is it the PC Compatibility Enhancer (aka PCCEj? If so, there looks to be a copy on 8BS disc 512-3-1 (BBC PD 512)

Edit: and apparently pages of M512 information at http://www.cowsarenotpurple.co.uk/bbcco ... tware.html

There’s also PC Solver 1 and 2 which I believe are on *. which may also solve some compatibility issues….some

Edit: Found it viewtopic.php?p=191308#p191308 and manual https://www.stardot.org.uk/forums/viewt ... 76#p356976