Lobo's Max-80

[aliensrcooluk at yahoo.co.uk]

Hi all,

Basically, I bought a bunch (40) of 
80 Microcomputing magazines which are in
pretty much mint condition. Every so often
I type up interesting articles and post them
to a couple of groups I am a member of.

Since I am new here, I don't know whether
this is allowed or not. If not, just let me
know.





A long read, but quite an interesting one. I 
was trying to keep this short, but I ended up 
typing up most of the article!


Source: Page 122, 80 Microcomputing #42 (July 
1983) - a Wayne Green Publication.


Ignoring the adverts, the full length article 
about Lobo's (or Lobo Drives International, to 
give it it's full name) Max-80 computer is 4 
pages long and is written by R.A. Langevin. I 
have attempted to give a summary of all the 
interesting bits. Read on....


Lobo Systems' Max-80 is an 8-bit microcomputer 
that supports LDOS and CP/M; has an impressive 
array of storage options, including floppy and 
hard disks; serial input/output; and both serial
and parallel printer ports. In terms of 
versatility and performance per dollar, it's 
unquestionably a best buy in todays marketplace.

The system is a natural upgrade for [TRS-80] 
Model I owners since it offers CP/M while 
preserving their investment in disk drives and 
in much of their software. It is also 
completely at home in a business environment.

Not everyone, however, will appreciate this 
computer. Serious game players will find they 
can't use self-booting disks in the machine 
[what the?!]. In addition, although Model I 
graphics are supported and limited graphics 
are available in the CP/M mode, the Max-80 
cannot presently display full-screen, high 
resolution graphics, a deficiency that makes 
it unsuitable for some business uses.

The Max-80 is basically a single-board 
computer housed, with it's power supply, in an 
attractive, ivory coloured plastic case 
mounted on a steel baseplate. It complies 
with the radiation limits established by the 
FCC for Class A computing devices. Although 
this standard states that operation of 
complying equipment is likely to cause 
interference in residential areas, I have not 
encountered problems even with a television 
in the same room.

The Max-80 is 17.5 inches wide and 10 inches 
deep. The top of the machine is 2 inches off 
the table top at the front and slopes gently 
upward [like my Amiga 600] to 3.5 inches at 
the top of the keyboard. The rear of the 
case holds a line fuse and all the connectors 
and switches [sounds familiar]. The internal 
power supply operates off 110-115 volts AC 
and is efficient enough so that a fan isn't 
necessary to keep the electronics cool 
[computers needed fans back then?].  The 
entire computer requires only 28 watts. Even 
after hours of continous operation, the case 
is never warm to the touch. The reset button 
is safely located at the rear of the machine.

Except for an optional 64K bank of memory, 
the Max-80 is complete as it comes out of 
the box. There are no extra boards for disk 
interfaces, serial I/O, or video electronics. 
As a result, the machines original cost is its 
only cost.

The machine is available with LDOS 5.1 and 
CP/M 2.2; much of the available [TRS-80] Model
I and Model III software are supported as is 
8-bit CP/M software. This combination of 
operating systems provides access to a larger
software base than that of most competing 
machines.


 - CPU: Z80B @ 5.07 MHz 

(faster than TRS-80 I, II ,III & 12 and the Softcard
 Apple)

 - Realtime clock (years, months, days, hours 
and seconds, all accessible by software) with 
internal rechargeable battery
 - Keyboard features a 10-key numeric pad, 4 
programmable function keys and a cursor-
control block that includes a clear key. All 
ASCII keys are supported by auto repeat and 
the entire keyboard is fully debounced.

 - RAM supplied by one (or two) banks of 64K 
each, provided by 8 (or 16) Texas Instruments 
TMS 4164-20 chips.
 - Only 1 ROM which contains a small bootstrap
loader that disables once the system boots. 
As a result, the modified LDOS supplied with 
the system loads the bottom 12K of RAM with 
the code that resides in ROM on Tandy or LNW 
[who?] machines. Consequently, currently 
available self-booting disks don't operate on 
the Max-80.

 - Separate gold plated card edges for 
connecting 5 inch and 8 inch floppy drives 
(both supporting single and double density, 
aswell as single and double-sided, disks) and 
are supported by the built-in controller in both
TRS-80 and CP/M modes. A slide switch 
mounted adjacent to the 5 inch disk connector
controls pin 32, permitting it to select drive 4
or, alternatively, to act as the side-select 
signal when using double-sided drives. Track 
counts of 35, 40, 77 and 80 are supported on 
5 inch disks and the standard 77 tracks on 8 
inch disks.

 - A hard disk interface is also included in the
Max-80 and is available on a 50-pin, 
gold-plated card edge on the rear of the 
machine. This Shugart Associates Standard 
Interface (SASI) is designed to be used with 
an external controller. Both of the computers 
operating systems are presently configured to
use Lobo Systems' Universal Controller  and 
do not support other controllers without 
modification.

 - Maximum of 4 drives with LDOS, or 8 drives 
with CP/M. Since so many disk options are 
available they have included a DIP (Dual In-line
Package) switch is provided on the rear of 
the case so you can boot from either a 5 
inch (or 8 inch) floppy, 5 inch (or 8 inch) hard 
disk or a 5 inch (or 8 inch) floppy connected 
via the universal controller.
(If you have the extra 64K of memory installed,
it's possible to set up a ninth RAM: drive with 
1K of directory space and 63K of storage space)

 - 5 inch disks can be formatted in Lobo's 
single or double-sided, double density format 
or in Osbourne, Xerox 820 or Omikron single 
density, single sided formats

 - 8 inch disks can be formatted in IBM single 
sided, single density and double sided, single 
or double density formats.

 - Serial I/O is provided from 2 independently 
programmable RS-232 interfaces (provided by 
a Z80 SIO chip, rather than a UART chip as in 
Tandy's machines) accessible through DB-25 
connectors on the rear of the case. Either 
interface supports all standard baud rates up 
to 19,200 and can be used to drive a serial 
printer.

 - Parallel printer output is available via a 
standard Centronics interface, with a slide 
switch adjacent to the port which permits 
grounding or ungrounding pin 27 to adapt to 
printers (like the Epsom MX-80) that interpret 
a grounded pin 27 as a request to generate a 
line feed after each carriage return.

 - Video output is via a RCA phono jack and 
drives any monitor that accepts 1 volt 
composite video from a 75 ohm source and 
provides 15,750 Hz horizontal and 60Hz vetical 
sync frequencies.
Lobo recommends a monitor bandwidth 
extending from DC to atleast 12 MHz to obtain
good detail in the display, This is especially 
important in the CP/M mode, where the normal 
display is 80 characters by 25 lines. You can 
select a 40 character by 25 line display with a
function key. In the TRS-80 mode, the display 
is a compatible 64 or 32 characters by 16 lines.

 - Standard TRS-80 Model I graphics are 
supported by the LDOS operating system - the
extended graphics of the [TRS-80[ Model III 
are not. In the CP/M mode you can display up 
to 192 user-defined shapes. The first 128 
shapes are limited to shapes that can be 
defined in the top half of a 8x16 pixel 
rectangle (and in normal use are used to 
display the ASCII character set). The remaining
64 shapes can be defined in a full 8x16 pixel 
rectangle.


Max-80 with just 64K and CP/M 2.2 - $820 
LDOS 5.1 - $69
64K RAM expansion - $95
Amdek Video 300 Green Screen 12" Monitor - $175



Regards,
Andrew B
aliensrcooluk at yahoo.co.uk