By the title I mean a built in option rather than a software or hardware add on and saving / loading to regular domestic audio cassette tape.

We should exclude all third party type loaders from this aka "hyperload" or such as it is only aimed at built in options please.

I aware of the Oric offering a selectable 2400 or 300 rate as well as the BBC Micro (possibly Electron too but I cannot confirm that) offering a 1200 and 300 rate. The Amstrad CPC range also offers 1000 or 2000.

Question is as per the title , what other machines offered this choice as a built in option please ?

  • 2
    This question sounds much like asking for a list, which is frowned upon. Do you see a chance to change this?
    – Raffzahn
    Jan 8, 2020 at 0:54
  • 1
    Does read that way sorry. I could not see how to phrase it better. Was more really a case of how widespread the option was rather than a complete listing ( which is unfair to ask for ) I am happy to accept edits to the question to re-phrase it though if required :)
    – AndyF
    Jan 8, 2020 at 2:16

3 Answers 3


I'd say a rather large number of early systems did - maybe even a majority.

A quick list from memory:

(On purpose not exhaustive, only meant to show that there were many - and for a reason)

  • Processor Technology SOL-PC/10/20
  • Any S100 machine with a Processor Technology CUTS board
  • Exidy Sorcerer
  • Acorn Atom/BBC
  • Heathkit H8
  • NASCOM-1/-2
  • OSI C1P
  • TA Alphatronic PC
  • MSX (1200/2400)

All of them and many more offered a 300/1200 Bd storage. The reason lays within the topmost two entries, as Prozessor Technologies CUTS board, bzw. the SOL-PC/SOL-20 was used as base for the Kansas City standard used by the large majority of early systems. While only compatibility was required for 300 Bd, many implemented 1200 Bd as well.

MSX systems are a bit of an outlier here, as the lowest speed offered it a KCS compatible 1200 Bd, while the 2400 Bd uses the same format but modified frequencies.

  • 2
    Also TRS-80 and SAM Coupé. Jan 8, 2020 at 0:57
  • A soviet Vector-06c had a built-in capability to automatically adjust to a tape recording baud rate in its ROM "bootloader". In Basic or the monitor software (think bare-bones assembler / disassembler / debugger), though, one would have to set the so called "tape read / write constant" manually.
    – DmytroL
    Jan 14, 2020 at 13:15

The Panasonic Jr.200 offered a choice of 600 or 2400 baud rates for tape saves, selectable via a switch on the bottom of the computer.

  • Thank you. That is actually one thought or idea that had escaped me: A built in physical switch for baud rate apposed to the more common software option to select it :)
    – AndyF
    Jan 10, 2020 at 16:51

The C64 didn't use the typical FSK format, but could emit and interpret flux reversals with flexible timing. Changing the baud rate was simply a matter of using different timing values with one of the CIAs. The hardware involved was exceedingly simple, and relied much more on software assistance than in many other micros.

With this flexibility, "fastloaders" which increased the data rate considerably over the standard format were common.

  • 1
    This got flagged as not an answer, and I think it is excluded as the question seems to refer specifically exclude these: "We should exclude all third party type loaders from this aka "hyperload" or such as it is only aimed at built in options please." That said, if you've got some details around the hardware specifically supporting different rates that could make it work!
    – Matt Lacey
    Jan 11, 2020 at 0:00
  • 1
    @MattLacey The whole point is that the C64 hardware didn't constrain the available baud rates. It was just a flux reversal generator/detector to be used in conjunction with the CIA timers.
    – Chromatix
    Jan 11, 2020 at 7:01
  • @Chromatix But isn't that the case for a lot of different computers? I believe that the Apple II, FM-7 series and the JR-200, and probably many others, all just used simple zero-crossing detectors and internal timers rather than anything (such as perhaps a UART) that would constrain the baud rate.
    – cjs
    May 14, 2023 at 1:56

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