After 45 days in jail playing poker for cigarettes, it was a pleasure, Doc said, to get back to the card rooms and the "real poker players."

And so there he was at 11 a.m. at the Plaza Card Room on 4th Avenue, wearing his lucky mohair hat, his pyramid power ring and a sports coat over his undershirt.

And it was with cool effrontery that he introduced himself to the table as "Doc," even though he certainly realized that almost everyone has been cautioned: "Never play poker with a man named Doc."

Doc is part of a Runyonesque crowd that from 10 a.m. to midnight six days a week patronizes the dozen or so legal card rooms clustered along 4th Avenue.

Often they are known to their cardplaying cronies only by nicknames -- Tuna Charlie, Tall Bob and Rivers, so named because of his penchant for saying, "Buddy, I'd wade across a river to call that bet."

Their bond is a love of poker that consumes most of their time and money.

"To some people cards are a diversion," Doc said. "But a real poker player is compulsive."

After he got out of jail, Doc said, he ran a small stake up to $1,000 and was playing in one of the big games at the Lucky Lady on El Cajon Boulevard.

But now he was broke again, reduced to the nickel-ante lowball game at the Plaza on 4th.

Although most of the good players play only for recreation, many card-room habitues like Doc see their $5 stake -- the minimum needed to buy into the cheapest game -- as "a window to the world," according to the card-room owner, Lincoln Pickard.

"Through that window they see everything they have ever wanted," he said. Pickard, who owns Link's on 4th Avenue, was himself a regular player in the downtown San Diego card rooms for 14 years.

"I've never known anybody ever making it big playing poker, and few can even eke out a living playing cards. But a lot of people here on the street think they can take $5 and run it into a fortune."

There are 70 licensed card rooms in San Diego and another 30 in adjacent cities, including two in La Jolla. All of the card rooms offer either five-card draw or California lowball, the latter a game in which the lowest hand wins.

In the California version of lowball the lowest hand is a "wheel" or "bicycle," ace through 5, and straights and flushes don't count.

"I'd say about 90 percent of the players are regulars," Pickard said. "Playing poker is the mainstay of their social life."

According to players, owners and "house men" (the card-room managers), the best pickings are at the first of the month, when pension checks arrive.

By the end of the month, the games are small and tight and many of the players are "on the edge," trying desperately to run up their last few dollars into a stake they hope will take them into a bigger game or even finance a trip to Las Vegas.

Although some of the card-room owners are inclined to paint their downtown establishments as merely recreation centers for senior citizens, other observers see the card rooms in a different light.

"It makes you sad sometimes to see the welfare people and pensioners losing their money in here," one house man said. "For them that money is a matter of survival, and when they go broke they hock their ring for five bucks to get back into the game. Gambling is a sickness. And it's a disease I've got myself."

But at Benjie's Card Room at the corner of 4th Avenue and F Street, on any afternoon, the old-timers, the "hard rocks" playing in the $2 to $4 lowball game, show no outward signs of desperation.

At the card rooms on El Cajon Boulevard featuring high-stakes games, the house employs professional dealers to lessen the chance of cheating.

But in the downtown card rooms, the deal rotates among the players just as it does at a friendly game around the kitchen table.

"We have to keep a constant eye out for cheaters, said Arthur Hubbard, house man at Leroy's Card Room. It's the house's job to protect the customer and the success of a room depends on its reputation for honesty."

Usually, Hubbard said, it's easy to spot the card mechanics because the adept cheats don't waste their time on the small games around 4th Avenue.

Hubbard, who 15 years ago worked as a dealer in a "flat joint" (crooked room), said that because the house makes its profit from the "post time," the half-hourly seat rent ranging from 60 cents to $1.25, it doesn't pay to condone cheating.

"If I spot anything funny, I cash the guy out in a hurry," Hubbard said.

To make a profit, the card rooms have to keep their tables going constantly during the legal hours.

Nothing is more deadly to the spirit of a cautious player than to enter a card room at 10:15 a.m. to find three shills and the house man sitting around a table glumly clacking their chips while waiting for a real player to show up.

In an effort to induce early play, some houses, such as the Plaza Card Room, offer free coffee and doughnuts between 10 a.m. and noon or a free sandwich for the first lowball "wheel" drawn each hour.

Also, the house men and even the owners have to sit in to get games started or keep them going. And all the houses use shills.

"You're not really supposed to do it," said Denton Leonard, owner of Leroy's, "but every house 'cows up' with players or stakes them to get the games started."

In a "cowing up" arrangement, the house furnishes 50 percent of the shill's stake. If the shill wins, he must turn over half of his winnings to the house.

Players on 4th Avenue fall easily into three types. There are the small-time hustlers and compulsive gamblers, the Docs, who cling to the dream of making a big score by playing cards.

There are the pensioners, who play for amusement and enjoy the card-room socializing.

And there are what one house man calls "the blue-collar types" who have regular jobs and play only for a few hours in the evening or on their lunch hours, like the liquor distributor who rushes into a card room for a few quick hands between deliveries.

Some card-room poker players manage -- temporarily, at least -- to shake their addiction to cards.

"When I arrived in San Diego from Chicago, I came straight to the card rooms and played 14 hours a day for a month," Lester said. "It was the best run of cards I've ever had and at the end of the month I counted my money and I had $300 more than I started with.

"That's the best I've ever done."

Lester, who now works as a cook in a downtown cafe, said he once was one of those "with the dream of the big car and 10 suits that I'd have just as soon as I built up my stake.

"I'd see a lot of guys make a little bundle and take off for Vegas, and two weeks later they're back chipping nickels in the little lowball game, or cowing up with the house with their last two bucks."

But with the pensioners it is different, said Leonard, whose high-draw game at Leroy's caters mainly to the seniors.

"They don't lose much and they don't win much," Leonard said. "Playing cards gives them something to do. It's better than sitting around the hotel all day."