4 ms·

At university I had to code an emulator in assembly and I thought how much more fun it would have been to use some old 8-bit micros. I've got a BBC B+128KB and

by forinti 16y ago

At university I had to code an emulator in assembly and I thought how much more fun it would have been to use some old 8-bit micros. I've got a BBC B+128KB and the coolest thing about them is that you can mix BASIC and assembly.

jacquesm 16y ago
Ah, the '[' trick, I remember when I first found out about that and thought it the neatest trick ever, no need to have a separate assembler. That said, it was mostly useful to speed up basic programs, if you wanted to write a program completely in assembler there were better options (the 'ade' rom for instance). I still have a 'mostly functional' bbc emulator that I wrote for the ST laying around, there are much better ones available now so there is no point releasing the thing, but it was lots of fun to code that up, the 6502 part is about 1600 loc, the rest of the project another 1600 lines or so. I never did implement mode 7 (teletext) or sound, but most of the other stuff worked. Can you still read your old media?
- forinti 16y ago
  All of my cassettes and most of my 5,25" floppies don't work. My drives are also starting to fail, so I recently got some new 3,5" drives installed and wrote about it here (portuguese only, I'm afraid): http://alquerubim.blogspot.com/2010/07/upgrade-historico.html http://alquerubim.blogspot.com/2010/07/upgrade-historico.htm... The only floppies that still work are those that came in those nice black folders from Acornsoft.
  - jacquesm 16y ago
    With cassettes the problem is usually copy-through, with one layer influencing the next on the wound up spools so you get pre and post echos of the signal. You can possibly fix that using a bunch of processing. The disks is a harder problem, surprising though, that they've already degraded that much, I would have expected the 5 1/4" to be readable a bit longer than this.
    - forinti 16y ago
      Well, this is Brazil (hot and humid) and they did have to endure about 10 years in my dad's shed, so I didn't really expect them to still work. The BBC, on the other hand, only requires maintenance on the power source's capacitors every 10 years or so (I've changed them twice so far). It's quite a sturdy machine!
      - jacquesm 16y ago
        Yes, electrolytic caps tend to dry out over time. There are special ones that are mil-spec that don't have that problem, or you could try your luck with Tantalum. The Sprague brand used to have fairly affordable long life electrolytic caps, maybe you can find those where you live or order them online. That way it's a one time affair. On another note, if you open up the power supply you'll find a bunch of coils in there, some of them are fairly loosely wound, eventually the windings will rub their way through the insulation and short out. It's not a bad idea to put some hotmelt on those windings to dampen the vibration. Just a little line on either side will do wonders.
- RichardRussell 16y ago
  Using '[' to enter the assembler still works in BBC BASIC for Windows, except that of course it accepts IA-32 (x86) instructions rather than the 6502 instructions of the old BBC Micro. The power of being able to mix BASIC and assembler code in the same program is as great as ever. BBC BASIC for Windows does implement MODE 7 (teletext) and the SOUND statement! http://www.bb4w.com/ http://www.bb4w.com/

by forinti 16y ago

jacquesm 16y ago

Ah, the '[' trick, I remember when I first found out about that and thought it the neatest trick ever, no need to have a separate assembler. That said, it was mostly useful to speed up basic programs, if you wanted to write a program completely in assembler there were better options (the 'ade' rom for instance). I still have a 'mostly functional' bbc emulator that I wrote for the ST laying around, there are much better ones available now so there is no point releasing the thing, but it was lots of fun to code that up, the 6502 part is about 1600 loc, the rest of the project another 1600 lines or so. I never did implement mode 7 (teletext) or sound, but most of the other stuff worked. Can you still read your old media?

forinti 16y ago
All of my cassettes and most of my 5,25" floppies don't work. My drives are also starting to fail, so I recently got some new 3,5" drives installed and wrote about it here (portuguese only, I'm afraid): http://alquerubim.blogspot.com/2010/07/upgrade-historico.html http://alquerubim.blogspot.com/2010/07/upgrade-historico.htm... The only floppies that still work are those that came in those nice black folders from Acornsoft.
- jacquesm 16y ago
  With cassettes the problem is usually copy-through, with one layer influencing the next on the wound up spools so you get pre and post echos of the signal. You can possibly fix that using a bunch of processing. The disks is a harder problem, surprising though, that they've already degraded that much, I would have expected the 5 1/4" to be readable a bit longer than this.
  - forinti 16y ago
    Well, this is Brazil (hot and humid) and they did have to endure about 10 years in my dad's shed, so I didn't really expect them to still work. The BBC, on the other hand, only requires maintenance on the power source's capacitors every 10 years or so (I've changed them twice so far). It's quite a sturdy machine!
    - jacquesm 16y ago
      Yes, electrolytic caps tend to dry out over time. There are special ones that are mil-spec that don't have that problem, or you could try your luck with Tantalum. The Sprague brand used to have fairly affordable long life electrolytic caps, maybe you can find those where you live or order them online. That way it's a one time affair. On another note, if you open up the power supply you'll find a bunch of coils in there, some of them are fairly loosely wound, eventually the windings will rub their way through the insulation and short out. It's not a bad idea to put some hotmelt on those windings to dampen the vibration. Just a little line on either side will do wonders.
RichardRussell 16y ago
Using '[' to enter the assembler still works in BBC BASIC for Windows, except that of course it accepts IA-32 (x86) instructions rather than the 6502 instructions of the old BBC Micro. The power of being able to mix BASIC and assembler code in the same program is as great as ever. BBC BASIC for Windows does implement MODE 7 (teletext) and the SOUND statement! http://www.bb4w.com/ http://www.bb4w.com/