ZX8301
Encyclopedia
The ZX8301 was a ULA integrated circuit
designed for the Sinclair QL
microcomputer
. Also known as the "Master Chip", it provided a Video Display Generator, the division of a 15 MHz crystal to provide the 7.5 MHz system clock, ZX8302
register address decoder
, DRAM
refresh and bus controller. The ZX8301 was IC22 on the QL motherboard
.
The Sinclair Research business model had always been to work toward a maximum performance to price ratio (as was evidenced by the keyboard mechanisms in the QL and earlier Sinclair models). Unfortunately this focus on price and performance often resulted in cost cutting in the design and build of Sinclair's machines. One such cost driven decision (failing to use a hardware buffer IC between the IC pins and the external RGB monitor connection) caused the ZX8301 to quickly develop a reputation for being fragile and easy to damage, particularly if the monitor plug was inserted or removed while the QL was powered up. Such an action resulted in damage to the video circuitry with the ZX8301 almost always requiring replacing.
The ZX8301, when subsequently used in the ICL One Per Desk
featured hardware buffering and as a direct result, the ZX8301 ULA was proven to be much more reliable.
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
designed for the Sinclair QL
Sinclair QL
The Sinclair QL , was a personal computer launched by Sinclair Research in 1984, as the successor to the Sinclair ZX Spectrum...
microcomputer
Microcomputer
A microcomputer is a computer with a microprocessor as its central processing unit. They are physically small compared to mainframe and minicomputers...
. Also known as the "Master Chip", it provided a Video Display Generator, the division of a 15 MHz crystal to provide the 7.5 MHz system clock, ZX8302
ZX8302
The ZX8302 was a ULA integrated circuit designed for the Sinclair QL microcomputer. Also known as the QL's "Peripheral Chip", it interfaced the CPU to the Microdrives, QLAN local area network interface and RS-232 ports and also provided a real-time clock. The ZX8302 was IC23 on the QL motherboard....
register address decoder
Address decoder
In digital electronics, an address decoder is a decoder circuit that has two or more bits of an address bus as inputs and that has one or more device selection lines as outputs. When the address for a particular device appears on the address bus, the address decoder asserts the selection line for...
, DRAM
Dram
Dram or DRAM may refer to:As a unit of measure:* Dram , an imperial unit of mass and volume* Armenian dram, a monetary unit* Dirham, a unit of currency in several Arab nationsOther uses:...
refresh and bus controller. The ZX8301 was IC22 on the QL motherboard
Motherboard
In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...
.
The Sinclair Research business model had always been to work toward a maximum performance to price ratio (as was evidenced by the keyboard mechanisms in the QL and earlier Sinclair models). Unfortunately this focus on price and performance often resulted in cost cutting in the design and build of Sinclair's machines. One such cost driven decision (failing to use a hardware buffer IC between the IC pins and the external RGB monitor connection) caused the ZX8301 to quickly develop a reputation for being fragile and easy to damage, particularly if the monitor plug was inserted or removed while the QL was powered up. Such an action resulted in damage to the video circuitry with the ZX8301 almost always requiring replacing.
The ZX8301, when subsequently used in the ICL One Per Desk
One Per Desk
The One Per Desk, or OPD, was an innovative hybrid personal computer/telecommunications terminal based on the hardware of the Sinclair QL. The One Per Desk was built by International Computers Limited and launched in the UK in 1984...
featured hardware buffering and as a direct result, the ZX8301 ULA was proven to be much more reliable.