Hermes
A replacement IC for the QLs 8049 co-processor
January 26, 2003
The Sinclair QL's second processor - the Intelligent
Peripheral Controller (IPC 8049) handles sound, serial input and
keyboard input. The internal code of the 8049 suffers a number of
problems, some fatal.
- Serial input suffers from bad handshaking which
can result in at best loss of characters, and at worst
'serial overrun' (input out of step with screen) which
can only be cured with a power down.
- Keyboard handling Key rollover doesn't work and
some keyboards, especially the Schoen and Keyboards
Products, suffer from keybounce. There is a 'debounce'
8749 available, but this destroys serial input.
- Baud rates Independent baud rates are not
possible. Input at 9600bps requires 2 stop bits, and
19200 input is impossible.
- Sound 'Fuzzy' and 'Random' on sound shift the
underlying pitch. Sound duration is dependent on pitch.
All the above problems are cured by Hermes
- No keyboard bounce
- Two key rollover, even with SHIFT
- Fully reliable serial input up to 19200bps - use any
modem without Qconnect (This assumes that the
input/output buffers (ICs 25/ 26) are fully functional,
and that handshaking is enabled at both ends and
connected).
- Code to handle spare input/output lines. One of these is
used by the Qview capsled kit.
- Different baud rates for each ser1 and ser2 input line,
and separate from output. This can be used to drive a
serial mouse (ser2) and printer (ser1) at the same time.
Open/closed status of serial ports can be read.
- Keyclick can be toggled on and off.
- Function to return IPC version number.
Fitting is a simple job - simply remove the top of the QL (8
screws) and replace the IC marked '8049' next to microdrive 1. A
small file is RESPRed for the extended features.
Prices: UK Europe Rest of world
Files are available for download
(25 Aug 96)
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