Maťo
It was manufactured from 1989 by Štátny majetok Závadka nad Hronom.
The computer was inspired by or was successor to BAPO. Hardware is based on MHB8080A @ 2,048 MHz, 48 KiB RAM, 16 KiB ROM.
Parts of this topic may be machine translated.
PMD85 clone (PMD85.1 and PMD85.2 variants) with minor modifications. The main goal of BAPO/MAŤO was to build a computer compatible with the PMD 85, but cheaper and smaller.
Hardware
The entire computer is located on one printed circuit board. Another board contained a power supply including a mains transformer.
- MHB 8080A processor @ 2.048 MHz
- RAM: 48 KB
- ROM: 16 KB
- interface for a standard cassette recorder
- monochrome output to TV, resolution 288×256 points
Software
* system monitor and built-in BASIC-G
Computer network "Maťo-LAN"
The manufacturer has proposed an innovative design that enables the use of a microcomputer in a local network, e.g. in a school classroom. This network was delivered and assembled by the company as a complete solution.
The development of the system, inspired by the TOKEN RING architecture, brought the following local area network (LAN) features:
- Resident software that extends MONITOR system commands with support for LAN (READ, SEND, SET) and occupies only 2 KB of memory.
- A concentrator using the MHB8748 single-chip microcomputer, allowing the connection of up to 31 satellite computers with equal access to the network.
- The possibility of connecting a superior IBM-PC type computer as a FILE SERVER through a special card connected directly to the concentrator.
- Transfer rate of 1200 bits per second with serial "handshake" protocol support for each byte, using a 20mA current loop.
- Ability to transfer all types of data blocks and programs used by these types of microcomputers.
- The possibility of direct connection of two ONLINE computers without a concentrator with the support of LAN data transfer software.
- Easy implementation of technical (concentrator) and software resources on other mentioned types of computers.
- Structured LAN software provides basic services for user application programs.
CHANNEL CONCENTRATOR
The main device of the network is a 31-channel concentrator, designed for a STAR-RING type local network topology, which enables an ON-LINE connection between any two network participants as follows:
- The concentrator checks the connection request using circular sequential search (POOLING). If it detects a transfer request (IN=H), it reads the transfer header from which it determines the service type and recipient number.
- Checks the sender number. If it does not match the actual number, it corrects it in the transmission header and sends this modified header to the recipient.
- After passing the transmission header to the addressee, it connects the path between the sender and the addressee and checks the communication between the participants using passive eavesdropping.
- If there are no level changes on the IN line (=L) within 2 seconds, it declares the transfer as complete and continues to search at the next address.
It should be mentioned the concentrator's internal service, which is provided on the basis of the READ 00G command - the requester receives the status of network participants from the concentrator.
As for the technical solution of the concentrator, it is based on the MHB8748 single-chip microcomputer. The connections of the participants are provided by two MH74150 multiplexers and two MH74154 demultiplexers, along with other supporting circuits. The block diagram of the concentrator and the specific connection of one bidirectional channel of the current loop of the participant are shown in the attached figure.
In terms of communication between the CONCENTRATOR and the PARTICIPANT, the concentrator has an internal address of 00, which determines the number of participant channels. It follows that all participants have the same priority. Channel 1F must be used for the parent computer!
References