First post, by Robin4
- Rank
- l33t
http://www.technick.net/public/code/cp_dpage. … uide_umg_05_001
A long time ago its really makes me wonder how different type of simms where working.. I know that there where 30 pin simms and later 72 pin simms ( now i only have mentioned the fast page ones)
But today i was looking for more information about it and found this:
SIMMS
As previously mentioned, the term SIMM stands for Single In-Line Memory Module. With SIMMs, memory chips are soldered onto a modular printed circuit board (PCB), which inserts into a socket on the system board.
The first SIMMs transferred 8 bits of data at a time. Later, as CPUs began to read data in 32-bit chunks, a wider SIMM was developed, which could supply 32 bits of data at a time. The easiest way to differentiate between these two different kinds of SIMMs was by the number of pins, or connectors. The earlier modules had 30 pins and the later modules had 72 pins. Thus, they became commonly referred to as 30-pin SIMMs and 72-pin SIMMs.
Another important difference between 30-pin and 72-pin SIMMs is that 72-pin SIMMs are 3/4 of an inch (about 1.9 centimeters) longer than the 30-pin SIMMs and have a notch in the lower middle of the PCB. The graphic below compares the two types of SIMMs and indicates their data widths.
What i know about this is that an 286 system would be 16-bit machine (thats why only one or two simms are needing to get an booting machine.. And an 386 machine would be 32-bit machine, because it needs 4 simms to make an bootable system.
But iam still have some question that still havent an answere.
-When could cpus read the data in 32-bit chunks? And was this by design or implemented as instruction set? I think this roll-over was in the period of the 486 processor (because they introduced the 72-pin simms then)
- I also know that the earlier 486 boards has still 30 pin simm on the motherboard and didnt had sockets for 72-pins already.. Where these 30-pins really a draw-back in system / processor performance.. Because what iam think of that if a processor could read data in 32-bit chunks that is really would hold on performance..
- If an 30 pin simm could transfer 8-bits of data at a time, how is this data stored in these memory chips? Would it be that every bit is stored in on memory chip? (if the simm has 9 chips in the stick)
~ At least it can do black and white~