BIOSes
The CP/M operating system requires a BIOS (Basic I/O
System) to interface with the hardware of the machine, since
the BDOS (Basic Disk Operating System)
component is hardware-independent.
All machines built or modified by the ORD-GROUP ran CP/M 2.2 so we had to
write BIOSes for them.
ORBIOS
The first BIOS we wrote was for the ORDINATOR and was appropriately
called ORBIOS. We wrote it from scratch during the summer of
1984, using the EXIDY. Our BIOS initially didn't support IOBYTE, but
it supported a virtual C: disk and worked well.
SEBIOS
After ORBIOS was up and running, we built a floppy drive unit for
a second EXIDY machine. The unit's hardware was purposely designed
to be very similar to the ORDINATOR so that we could easily adapt
the ORBIOS to it. The result of this was called SEBIOS.
It added IOBYTE support, which was promptly back-ported to ORBIOS.
TS
The ORDINATOR Timesharing software (TS) implements the CP/M BIOS
interface for multiple processes at once, but it was written from
scratch and is described elsewhere.
ALIEN
Somewhere late in 1985, we added ALIEN support to ORBIOS,
which meant that we could now support foreign disk formats.
This was a major innovation, which was never backported to
SEBIOS, mainly because we didn't much use the EXIDY anymore,
preferring our own ORDINATOR instead. This history of
ALIEN is more fully described in the
ALIEN3.DOC document.
TVBIOS
In 1986, we modified ORBIOS once again to support the new
TELEVERKET hardware, calling the result TVBIOS. The most challenging
part of this exercise was the video display driver because of
the complexity of the hardware. No other innovations were added,
but the ALIEN support was of course duly copied.
SVBIOS
When the DISKSERVER hardware was completed, another ORBIOS
adaptation was done, resulting in SVBIOS. Because the
DISKSERVER had a more complicated disk subsystem, changes had to be
made that disabled ALIEN support for the machine. This was
also the first and only BIOS to acquire partition support,
which was needed for the hard disks. Shortage of drive letters
(CP/M supports only sixteen of them, A: through P:) proved to
be a problem then, but we managed. The ALIEN support was
later overhauled to support the SERVER program
but a program to install ALIEN descriptions was never completed.
CHAOS
After the DISKSERVER, we became somewhat tired of writing BIOSes.
Accordingly our next machine, of which we envisioned to build
several, was designed without disks and appropriately christened
DISKLESS.
We wanted to run CHAOS on these machines, which
was to be a network operating system that would not use the
CP/M 2.2 BDOS and hence not require a BIOS. Only a single
DISKLESS ever got built, however, and we never arrived at the
point of actually starting to implement CHAOS,
although a large amount of design work had been done.