For Sale – HSIN Digital cassette system, save & load files at 6000bps (equivalent 7,500 baud CUTS). Software control in 2x2708 + lots of software on digital cassette. Cost £350 inc 9 certified digital (mini) cassettes, will accept £175 ono
Gemini EPROM board with 8x2716 + 8x2708, total cost £100, only £50
Bits & PC’s PCG board. Programmable character generator + software. Cost £70, only £40. Castle cassette enhancing unit. Cost £20, only £10.
Phone ____-______

For Sale – Nascom 2, 48K RAM B, in vero rack, sound, manuals, Tandy monitor, lots of Micro Power games. £375 ono.
Phone _____-____

For Sale – I/O Systems High Resolution Board with software and documentation. £45 or exchange for a RAM A.
Nas-Sys ROM £9
Ring _____-____ evenings

Software Standards

by Rory O’Farrell

For some years now, Nascom users have been fortunate in having available to them one of the best machine code monitors for microprocessors. The limits of memory within which Richard Beale worked to write nas-sys 1 & 3 are now not as tight, in view of the drop in memory prices over the last two years and the ready availability of 64K machines at a reasonable price.

The journal of the Nascom users is the proper place to start a discussion on how such a monitor ought now to be extended. We are no longer tied to tight memory constraints. Chris Blackmore, with his MONITOR.COM has shown how Nas-sys can be adapted to run on CP/M based systems. Nas-sys 3 uses’ only 63 of the 256 possible ’Sys calls. Extensions to ’Sys were suggested as possible for the Nascom AVC card. Real Time Clocks can be purchased or built to run off a pair of PIO ports. A number of 80-column display cards are on the market. Three (more now) colour display cards are currently available.

Each of these items needs driving software. Such software is dependant on the particular hardware configuration used an the object being driven. For example, my RTC circuit, homebrewed, uses an inverted chip select to that written about by David Hunt in 80-Bus News No. 4. In consequence, I have to use (slightly) different driving software which has to be embedded in a program or accessible in a standard way. I suggest that the standard way for Nascom users should be through the calling conventions of Nas-sys.