The early 1980s were the scene of the first attempts at integrating separate chips into "All In One" encompassing packages, aka ULAs, or Uncommitted Logic Arrays. The majority of computer manufacturers (with the exception of Acorn and their BBC A/B) were engaging companies such as Ferranti to take anything up to 15 or 20 individual chips and integrate them into 40 pin DIL or PLCC style packages. Witness the reduction in chip count between the Sinclair ZX80 and ZX81, in little under a year the number of chips was reduced from 21 to as little as 4 to 5 chips (depending on 1k memory fitted). The early 80s were indeed a hotbed (!) of development and ironically hotbed was often the end result.
Heat was a major issue for the early computers and a ULA chip cooking itself into oblivion was often a concern for the early computer programmers. At one stage it was often a joke that the best way to keep a ZX81 cool was to perch a carton of cold milk on top of the black ABS case. The ZX Spectrum was not much better, and yes even the mighty Acorn and their Electron computer was prone to heat related failures. Many a night and a can of aerosol freeze spray was spent nursing along the computer be operated.
From that early experience, and due to now dipping my toes back into the glory days of 8 bit technology, extending the life of the computer by removing the heat from the ULA chip is a must. Generally the CPU and memory chips behave whatever the temperature, but the ULA is often twitchy, either loosing control of the keyboard or the video output goes when the temp gets too high and extended operation will eventually damage the chip beyond repair. There are companies out there that still stock these chips but they are rare, getting rarer, and often cost the proverbial arm and leg.
An easy fix, used back then and still viable now, is the fitment of a 40pin DIL chip stick on heat sink. If fitting to a ZX81 there is plenty of room but on the ZX Spectrum (rubber key) some hacksawing to remove some of the fin sections is required due to the step in the keyboard area of the case. The Spec+ is not affected by such constraints and is an easy fit. Generally, and ZX81 and ZX Spectrum issues 1 to 3 are at risk of heat damage. Looking inside the case of an Electron a PLCC style heat sink can be fitted but will be tight to the case. The most reliable of the Spectrum series are those where the heat sink is fitted over the rear expansion port rather than down the right hand side of the PCB. These models also benefit from the later ULA releases where heating effects are engineered out via better manufacturing techniques. The BBC A/B series has no such issues due to construction via the use of separate logic chips. Dragon 32/64 machines have large air spaces inside the case and good ventilation so heating of the logic array is not an issue.
Generally I'm finding that if it's a first or second generation computer, with the motherboard fitted within a tight case with little or no ventilation then the fitment of an additional heat sink will help to reduce heat damage to the chip and extend the operational life span of the computer, hopefully for another 30 odd years.
Heat was a major issue for the early computers and a ULA chip cooking itself into oblivion was often a concern for the early computer programmers. At one stage it was often a joke that the best way to keep a ZX81 cool was to perch a carton of cold milk on top of the black ABS case. The ZX Spectrum was not much better, and yes even the mighty Acorn and their Electron computer was prone to heat related failures. Many a night and a can of aerosol freeze spray was spent nursing along the computer be operated.
From that early experience, and due to now dipping my toes back into the glory days of 8 bit technology, extending the life of the computer by removing the heat from the ULA chip is a must. Generally the CPU and memory chips behave whatever the temperature, but the ULA is often twitchy, either loosing control of the keyboard or the video output goes when the temp gets too high and extended operation will eventually damage the chip beyond repair. There are companies out there that still stock these chips but they are rare, getting rarer, and often cost the proverbial arm and leg.
An easy fix, used back then and still viable now, is the fitment of a 40pin DIL chip stick on heat sink. If fitting to a ZX81 there is plenty of room but on the ZX Spectrum (rubber key) some hacksawing to remove some of the fin sections is required due to the step in the keyboard area of the case. The Spec+ is not affected by such constraints and is an easy fit. Generally, and ZX81 and ZX Spectrum issues 1 to 3 are at risk of heat damage. Looking inside the case of an Electron a PLCC style heat sink can be fitted but will be tight to the case. The most reliable of the Spectrum series are those where the heat sink is fitted over the rear expansion port rather than down the right hand side of the PCB. These models also benefit from the later ULA releases where heating effects are engineered out via better manufacturing techniques. The BBC A/B series has no such issues due to construction via the use of separate logic chips. Dragon 32/64 machines have large air spaces inside the case and good ventilation so heating of the logic array is not an issue.
Generally I'm finding that if it's a first or second generation computer, with the motherboard fitted within a tight case with little or no ventilation then the fitment of an additional heat sink will help to reduce heat damage to the chip and extend the operational life span of the computer, hopefully for another 30 odd years.